sphinx.addnodesdocument)}( rawsourcechildren]( translations LanguagesNode)}(hhh](h pending_xref)}(hhh]docutils.nodesTextChinese (Simplified)}parenthsba attributes}(ids]classes]names]dupnames]backrefs] refdomainstdreftypedoc reftarget$/translations/zh_CN/filesystems/f2fsmodnameN classnameN refexplicitutagnamehhh ubh)}(hhh]hChinese (Traditional)}hh2sbah}(h]h ]h"]h$]h&] refdomainh)reftypeh+ reftarget$/translations/zh_TW/filesystems/f2fsmodnameN classnameN refexplicituh1hhh ubh)}(hhh]hItalian}hhFsbah}(h]h ]h"]h$]h&] refdomainh)reftypeh+ reftarget$/translations/it_IT/filesystems/f2fsmodnameN classnameN refexplicituh1hhh ubh)}(hhh]hJapanese}hhZsbah}(h]h ]h"]h$]h&] refdomainh)reftypeh+ reftarget$/translations/ja_JP/filesystems/f2fsmodnameN classnameN refexplicituh1hhh ubh)}(hhh]hKorean}hhnsbah}(h]h ]h"]h$]h&] refdomainh)reftypeh+ reftarget$/translations/ko_KR/filesystems/f2fsmodnameN classnameN refexplicituh1hhh ubh)}(hhh]hPortuguese (Brazilian)}hhsbah}(h]h ]h"]h$]h&] refdomainh)reftypeh+ reftarget$/translations/pt_BR/filesystems/f2fsmodnameN classnameN refexplicituh1hhh ubh)}(hhh]hSpanish}hhsbah}(h]h ]h"]h$]h&] refdomainh)reftypeh+ reftarget$/translations/sp_SP/filesystems/f2fsmodnameN classnameN refexplicituh1hhh ubeh}(h]h ]h"]h$]h&]current_languageEnglishuh1h hh _documenthsourceNlineNubhcomment)}(h SPDX-License-Identifier: GPL-2.0h]h SPDX-License-Identifier: GPL-2.0}hhsbah}(h]h ]h"]h$]h&] xml:spacepreserveuh1hhhhhh>/var/lib/git/docbuild/linux/Documentation/filesystems/f2fs.rsthKubhsection)}(hhh](htitle)}(h!Flash-Friendly File System (F2FS)h]h!Flash-Friendly File System (F2FS)}(hhhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhhhhhKubh)}(hhh](h)}(hOverviewh]hOverview}(hhhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhhhhhKubh paragraph)}(hXkNAND flash memory-based storage devices, such as SSD, eMMC, and SD cards, have been equipped on a variety systems ranging from mobile to server systems. Since they are known to have different characteristics from the conventional rotating disks, a file system, an upper layer to the storage device, should adapt to the changes from the sketch in the design level.h]hXkNAND flash memory-based storage devices, such as SSD, eMMC, and SD cards, have been equipped on a variety systems ranging from mobile to server systems. Since they are known to have different characteristics from the conventional rotating disks, a file system, an upper layer to the storage device, should adapt to the changes from the sketch in the design level.}(hhhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK hhhhubh)}(hXF2FS is a file system exploiting NAND flash memory-based storage devices, which is based on Log-structured File System (LFS). The design has been focused on addressing the fundamental issues in LFS, which are snowball effect of wandering tree and high cleaning overhead.h]hXF2FS is a file system exploiting NAND flash memory-based storage devices, which is based on Log-structured File System (LFS). The design has been focused on addressing the fundamental issues in LFS, which are snowball effect of wandering tree and high cleaning overhead.}(hhhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhhhhubh)}(hX1Since a NAND flash memory-based storage device shows different characteristic according to its internal geometry or flash memory management scheme, namely FTL, F2FS and its tools support various parameters not only for configuring on-disk layout, but also for selecting allocation and cleaning algorithms.h]hX1Since a NAND flash memory-based storage device shows different characteristic according to its internal geometry or flash memory management scheme, namely FTL, F2FS and its tools support various parameters not only for configuring on-disk layout, but also for selecting allocation and cleaning algorithms.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhhhhubh)}(hThe following git tree provides the file system formatting tool (mkfs.f2fs), a consistency checking tool (fsck.f2fs), and a debugging tool (dump.f2fs).h]hThe following git tree provides the file system formatting tool (mkfs.f2fs), a consistency checking tool (fsck.f2fs), and a debugging tool (dump.f2fs).}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhhhhubh bullet_list)}(hhh]h list_item)}(hEgit://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs-tools.git h]h)}(hDgit://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs-tools.gith]hDgit://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs-tools.git}(hj3hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj/ubah}(h]h ]h"]h$]h&]uh1j-hj*hhhhhNubah}(h]h ]h"]h$]h&]bullet-uh1j(hhhKhhhhubh)}(h;For sending patches, please use the following mailing list:h]h;For sending patches, please use the following mailing list:}(hjOhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhhhhubj))}(hhh]j.)}(h'linux-f2fs-devel@lists.sourceforge.net h]h)}(h&linux-f2fs-devel@lists.sourceforge.neth]h reference)}(hjfh]h&linux-f2fs-devel@lists.sourceforge.net}(hjjhhhNhNubah}(h]h ]h"]h$]h&]refuri-mailto:linux-f2fs-devel@lists.sourceforge.netuh1jhhjdubah}(h]h ]h"]h$]h&]uh1hhhhK!hj`ubah}(h]h ]h"]h$]h&]uh1j-hj]hhhhhNubah}(h]h ]h"]h$]h&]jMjNuh1j(hhhK!hhhhubh)}(hCFor reporting bugs, please use the following f2fs bug tracker link:h]hCFor reporting bugs, please use the following f2fs bug tracker link:}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK#hhhhubj))}(hhh]j.)}(hOhttps://bugzilla.kernel.org/enter_bug.cgi?product=File%20System&component=f2fs h]h)}(hNhttps://bugzilla.kernel.org/enter_bug.cgi?product=File%20System&component=f2fsh]ji)}(hjh]hNhttps://bugzilla.kernel.org/enter_bug.cgi?product=File%20System&component=f2fs}(hjhhhNhNubah}(h]h ]h"]h$]h&]refurijuh1jhhjubah}(h]h ]h"]h$]h&]uh1hhhhK%hjubah}(h]h ]h"]h$]h&]uh1j-hjhhhhhNubah}(h]h ]h"]h$]h&]jMjNuh1j(hhhK%hhhhubeh}(h]overviewah ]h"]overviewah$]h&]uh1hhhhhhhhKubh)}(hhh](h)}(hBackground and Design issuesh]hBackground and Design issues}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjhhhhhK(ubh)}(hhh](h)}(h Log-structured File System (LFS)h]h Log-structured File System (LFS)}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjhhhhhK+ubh)}(hX|"A log-structured file system writes all modifications to disk sequentially in a log-like structure, thereby speeding up both file writing and crash recovery. The log is the only structure on disk; it contains indexing information so that files can be read back from the log efficiently. In order to maintain large free areas on disk for fast writing, we divide the log into segments and use a segment cleaner to compress the live information from heavily fragmented segments." from Rosenblum, M. and Ousterhout, J. K., 1992, "The design and implementation of a log-structured file system", ACM Trans. Computer Systems 10, 1, 26–52.h]hX“A log-structured file system writes all modifications to disk sequentially in a log-like structure, thereby speeding up both file writing and crash recovery. The log is the only structure on disk; it contains indexing information so that files can be read back from the log efficiently. In order to maintain large free areas on disk for fast writing, we divide the log into segments and use a segment cleaner to compress the live information from heavily fragmented segments.” from Rosenblum, M. and Ousterhout, J. K., 1992, “The design and implementation of a log-structured file system”, ACM Trans. Computer Systems 10, 1, 26–52.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK,hjhhubeh}(h]log-structured-file-system-lfsah ]h"] log-structured file system (lfs)ah$]h&]uh1hhjhhhhhK+ubh)}(hhh](h)}(hWandering Tree Problemh]hWandering Tree Problem}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjhhhhhK7ubh)}(hXIn LFS, when a file data is updated and written to the end of log, its direct pointer block is updated due to the changed location. Then the indirect pointer block is also updated due to the direct pointer block update. In this manner, the upper index structures such as inode, inode map, and checkpoint block are also updated recursively. This problem is called as wandering tree problem [1], and in order to enhance the performance, it should eliminate or relax the update propagation as much as possible.h]hXIn LFS, when a file data is updated and written to the end of log, its direct pointer block is updated due to the changed location. Then the indirect pointer block is also updated due to the direct pointer block update. In this manner, the upper index structures such as inode, inode map, and checkpoint block are also updated recursively. This problem is called as wandering tree problem [1], and in order to enhance the performance, it should eliminate or relax the update propagation as much as possible.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK8hjhhubh)}(hQ[1] Bityutskiy, A. 2005. JFFS3 design issues. http://www.linux-mtd.infradead.org/h](h.[1] Bityutskiy, A. 2005. JFFS3 design issues. }(hj#hhhNhNubji)}(h#http://www.linux-mtd.infradead.org/h]h#http://www.linux-mtd.infradead.org/}(hj+hhhNhNubah}(h]h ]h"]h$]h&]refurij-uh1jhhj#ubeh}(h]h ]h"]h$]h&]uh1hhhhK@hjhhubeh}(h]wandering-tree-problemah ]h"]h$]wandering tree problemah&]uh1hhjhhhhhK7 referencedKubh)}(hhh](h)}(hCleaning Overheadh]hCleaning Overhead}(hjLhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjIhhhhhKCubh)}(hXSince LFS is based on out-of-place writes, it produces so many obsolete blocks scattered across the whole storage. In order to serve new empty log space, it needs to reclaim these obsolete blocks seamlessly to users. This job is called as a cleaning process.h]hXSince LFS is based on out-of-place writes, it produces so many obsolete blocks scattered across the whole storage. In order to serve new empty log space, it needs to reclaim these obsolete blocks seamlessly to users. This job is called as a cleaning process.}(hjZhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKDhjIhhubh)}(h4The process consists of three operations as follows.h]h4The process consists of three operations as follows.}(hjhhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKIhjIhhubhenumerated_list)}(hhh](j.)}(hEA victim segment is selected through referencing segment usage table.h]h)}(hj}h]hEA victim segment is selected through referencing segment usage table.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKKhj{ubah}(h]h ]h"]h$]h&]uh1j-hjxhhhhhNubj.)}(hdIt loads parent index structures of all the data in the victim identified by segment summary blocks.h]h)}(hdIt loads parent index structures of all the data in the victim identified by segment summary blocks.h]hdIt loads parent index structures of all the data in the victim identified by segment summary blocks.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKLhjubah}(h]h ]h"]h$]h&]uh1j-hjxhhhhhNubj.)}(hNIt checks the cross-reference between the data and its parent index structure.h]h)}(hjh]hNIt checks the cross-reference between the data and its parent index structure.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKNhjubah}(h]h ]h"]h$]h&]uh1j-hjxhhhhhNubj.)}(h!It moves valid data selectively. h]h)}(h It moves valid data selectively.h]h It moves valid data selectively.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKOhjubah}(h]h ]h"]h$]h&]uh1j-hjxhhhhhNubeh}(h]h ]h"]h$]h&]enumtypearabicprefixhsuffix.uh1jvhjIhhhhhKKubh)}(hThis cleaning job may cause unexpected long delays, so the most important goal is to hide the latencies to users. And also definitely, it should reduce the amount of valid data to be moved, and move them quickly as well.h]hThis cleaning job may cause unexpected long delays, so the most important goal is to hide the latencies to users. And also definitely, it should reduce the amount of valid data to be moved, and move them quickly as well.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKQhjIhhubeh}(h]cleaning-overheadah ]h"]h$]cleaning overheadah&]uh1hhjhhhhhKCjHKubeh}(h]background-and-design-issuesah ]h"]background and design issuesah$]h&]uh1hhhhhhhhK(ubh)}(hhh](h)}(h Key Featuresh]h Key Features}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjhhhhhKVubh)}(hhh](h)}(hFlash Awarenessh]hFlash Awareness}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjhhhhhKYubj))}(hhh](j.)}(h[Enlarge the random write area for better performance, but provide the high spatial localityh]h)}(h[Enlarge the random write area for better performance, but provide the high spatial localityh]h[Enlarge the random write area for better performance, but provide the high spatial locality}(hj+hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKZhj'ubah}(h]h ]h"]h$]h&]uh1j-hj$hhhhhNubj.)}(hIAlign FS data structures to the operational units in FTL as best efforts h]h)}(hHAlign FS data structures to the operational units in FTL as best effortsh]hHAlign FS data structures to the operational units in FTL as best efforts}(hjChhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK\hj?ubah}(h]h ]h"]h$]h&]uh1j-hj$hhhhhNubeh}(h]h ]h"]h$]h&]jMjNuh1j(hhhKZhjhhubeh}(h]flash-awarenessah ]h"]flash awarenessah$]h&]uh1hhjhhhhhKYubh)}(hhh](h)}(hWandering Tree Problemh]hWandering Tree Problem}(hjhhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjehhhhhK_ubj))}(hhh](j.)}(hPUse a term, “node”, that represents inodes as well as various pointer blocksh]h)}(hj{h]hPUse a term, “node”, that represents inodes as well as various pointer blocks}(hj}hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK`hjyubah}(h]h ]h"]h$]h&]uh1j-hjvhhhhhNubj.)}(hIntroduce Node Address Table (NAT) containing the locations of all the “node” blocks; this will cut off the update propagation. h]h)}(hIntroduce Node Address Table (NAT) containing the locations of all the “node” blocks; this will cut off the update propagation.h]hIntroduce Node Address Table (NAT) containing the locations of all the “node” blocks; this will cut off the update propagation.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKahjubah}(h]h ]h"]h$]h&]uh1j-hjvhhhhhNubeh}(h]h ]h"]h$]h&]jMjNuh1j(hhhK`hjehhubeh}(h]id1ah ]h"]h$]jFah&]uh1hhjhhhhhK_jHKubh)}(hhh](h)}(hCleaning Overheadh]hCleaning Overhead}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjhhhhhKeubj))}(hhh](j.)}(h%Support a background cleaning processh]h)}(hjh]h%Support a background cleaning process}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKfhjubah}(h]h ]h"]h$]h&]uh1j-hjhhhhhNubj.)}(hHSupport greedy and cost-benefit algorithms for victim selection policiesh]h)}(hjh]hHSupport greedy and cost-benefit algorithms for victim selection policies}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKghjubah}(h]h ]h"]h$]h&]uh1j-hjhhhhhNubj.)}(hGSupport multi-head logs for static/dynamic hot and cold data separationh]h)}(hjh]hGSupport multi-head logs for static/dynamic hot and cold data separation}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhhjubah}(h]h ]h"]h$]h&]uh1j-hjhhhhhNubj.)}(h:Introduce adaptive logging for efficient block allocation h]h)}(h9Introduce adaptive logging for efficient block allocationh]h9Introduce adaptive logging for efficient block allocation}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKihjubah}(h]h ]h"]h$]h&]uh1j-hjhhhhhNubeh}(h]h ]h"]h$]h&]jMjNuh1j(hhhKfhjhhubeh}(h]id2ah ]h"]h$]jah&]uh1hhjhhhhhKejHKubeh}(h] key-featuresah ]h"] key featuresah$]h&]uh1hhhhhhhhKVubh)}(hhh](h)}(h Mount Optionsh]h Mount Options}(hj>hhhNhNubah}(h]h ]h"]h$]h&]uh1hhj;hhhhhKlubhtable)}(hhh]htgroup)}(hhh](hcolspec)}(hhh]h}(h]h ]h"]h$]h&]colwidthKuh1jVhjSubjW)}(hhh]h}(h]h ]h"]h$]h&]colwidthKRuh1jVhjSubhtbody)}(hhh](hrow)}(hhh](hentry)}(hhh]h)}(hbackground_gc=%sh]hbackground_gc=%s}(hj{hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKphjxubah}(h]h ]h"]h$]h&]uh1jvhjsubjw)}(hhh]h)}(hXTurn on/off cleaning operations, namely garbage collection, triggered in background when I/O subsystem is idle. If background_gc=on, it will turn on the garbage collection and if background_gc=off, garbage collection will be turned off. If background_gc=sync, it will turn on synchronous garbage collection running in background. Default value for this option is on. So garbage collection is on by default.h]hXTurn on/off cleaning operations, namely garbage collection, triggered in background when I/O subsystem is idle. If background_gc=on, it will turn on the garbage collection and if background_gc=off, garbage collection will be turned off. If background_gc=sync, it will turn on synchronous garbage collection running in background. Default value for this option is on. So garbage collection is on by default.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKphjubah}(h]h ]h"]h$]h&]uh1jvhjsubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hgc_mergeh]hgc_merge}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKxhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hXWhen background_gc is on, this option can be enabled to let background GC thread to handle foreground GC requests, it can eliminate the sluggish issue caused by slow foreground GC operation when GC is triggered from a process with limited I/O and CPU resources.h]hXWhen background_gc is on, this option can be enabled to let background GC thread to handle foreground GC requests, it can eliminate the sluggish issue caused by slow foreground GC operation when GC is triggered from a process with limited I/O and CPU resources.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKxhjubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(h nogc_mergeh]h nogc_merge}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK}hjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hDisable GC merge feature.h]hDisable GC merge feature.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK}hjubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hdisable_roll_forwardh]hdisable_roll_forward}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK~hjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(h)Disable the roll-forward recovery routineh]h)Disable the roll-forward recovery routine}(hj7hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhK~hj4ubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(h norecoveryh]h norecovery}(hjWhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjTubah}(h]h ]h"]h$]h&]uh1jvhjQubjw)}(hhh]h)}(h`Disable the roll-forward recovery routine, mounted read- only (i.e., -o ro,disable_roll_forward)h]h`Disable the roll-forward recovery routine, mounted read- only (i.e., -o ro,disable_roll_forward)}(hjnhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjkubah}(h]h ]h"]h$]h&]uh1jvhjQubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hdiscard/nodiscardh]hdiscard/nodiscard}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hEnable/disable real-time discard in f2fs, if discard is enabled, f2fs will issue discard/TRIM commands when a segment is cleaned.h]hEnable/disable real-time discard in f2fs, if discard is enabled, f2fs will issue discard/TRIM commands when a segment is cleaned.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(h heap/no_heaph]h heap/no_heap}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(h Deprecated.h]h Deprecated.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(h nouser_xattrh]h nouser_xattr}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hhDisable Extended User Attributes. Note: xattr is enabled by default if CONFIG_F2FS_FS_XATTR is selected.h]hhDisable Extended User Attributes. Note: xattr is enabled by default if CONFIG_F2FS_FS_XATTR is selected.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hnoaclh]hnoacl}(hj3hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj0ubah}(h]h ]h"]h$]h&]uh1jvhj-ubjw)}(hhh]h)}(hkDisable POSIX Access Control List. Note: acl is enabled by default if CONFIG_F2FS_FS_POSIX_ACL is selected.h]hkDisable POSIX Access Control List. Note: acl is enabled by default if CONFIG_F2FS_FS_POSIX_ACL is selected.}(hjJhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjGubah}(h]h ]h"]h$]h&]uh1jvhj-ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hactive_logs=%uh]hactive_logs=%u}(hjjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjgubah}(h]h ]h"]h$]h&]uh1jvhjdubjw)}(hhh]h)}(hXSupport configuring the number of active logs. In the current design, f2fs supports only 2, 4, and 6 logs. Default number is 6. When the underlying block device exposes write streams, the default active_logs=6 configuration maps hot, warm, and cold DATA writes to streams 1, 2, and 3, respectively. If only one or two write streams are available, f2fs falls back to mapping all DATA writes to stream 1 or mapping hot/warm to stream 1 and cold to stream 2. If no write streams are exposed, f2fs leaves the stream unset.h]hXSupport configuring the number of active logs. In the current design, f2fs supports only 2, 4, and 6 logs. Default number is 6. When the underlying block device exposes write streams, the default active_logs=6 configuration maps hot, warm, and cold DATA writes to streams 1, 2, and 3, respectively. If only one or two write streams are available, f2fs falls back to mapping all DATA writes to stream 1 or mapping hot/warm to stream 1 and cold to stream 2. If no write streams are exposed, f2fs leaves the stream unset.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj~ubah}(h]h ]h"]h$]h&]uh1jvhjdubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hdisable_ext_identifyh]hdisable_ext_identify}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hfDisable the extension list configured by mkfs, so f2fs is not aware of cold files such as media files.h]hfDisable the extension list configured by mkfs, so f2fs is not aware of cold files such as media files.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(h inline_xattrh]h inline_xattr}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(h!Enable the inline xattrs feature.h]h!Enable the inline xattrs feature.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hnoinline_xattrh]hnoinline_xattr}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jvhj ubjw)}(hhh]h)}(h"Disable the inline xattrs feature.h]h"Disable the inline xattrs feature.}(hj&hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj#ubah}(h]h ]h"]h$]h&]uh1jvhj ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hinline_xattr_size=%uh]hinline_xattr_size=%u}(hjFhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjCubah}(h]h ]h"]h$]h&]uh1jvhj@ubjw)}(hhh]h)}(hSSupport configuring inline xattr size, it depends on flexible inline xattr feature.h]hSSupport configuring inline xattr size, it depends on flexible inline xattr feature.}(hj]hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjZubah}(h]h ]h"]h$]h&]uh1jvhj@ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(h inline_datah]h inline_data}(hj}hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjzubah}(h]h ]h"]h$]h&]uh1jvhjwubjw)}(hhh]h)}(hcEnable the inline data feature: Newly created small (<~3.4k) files can be written into inode block.h]hcEnable the inline data feature: Newly created small (<~3.4k) files can be written into inode block.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjwubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(h inline_dentryh]h inline_dentry}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hEnable the inline dir feature: data in newly created directory entries can be written into inode block. The space of inode block which is used to store inline dentries is limited to ~3.4k.h]hEnable the inline dir feature: data in newly created directory entries can be written into inode block. The space of inode block which is used to store inline dentries is limited to ~3.4k.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hnoinline_dentryh]hnoinline_dentry}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(h"Disable the inline dentry feature.h]h"Disable the inline dentry feature.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(h flush_mergeh]h flush_merge}(hj"hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hMerge concurrent cache_flush commands as much as possible to eliminate redundant command issues. If the underlying device handles the cache_flush command relatively slowly, recommend to enable this option.h]hMerge concurrent cache_flush commands as much as possible to eliminate redundant command issues. If the underlying device handles the cache_flush command relatively slowly, recommend to enable this option.}(hj9hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj6ubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(h nobarrierh]h nobarrier}(hjYhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjVubah}(h]h ]h"]h$]h&]uh1jvhjSubjw)}(hhh]h)}(hThis option can be used if underlying storage guarantees its cached data should be written to the novolatile area. If this option is set, no cache_flush commands are issued but f2fs still guarantees the write ordering of all the data writes.h]hThis option can be used if underlying storage guarantees its cached data should be written to the novolatile area. If this option is set, no cache_flush commands are issued but f2fs still guarantees the write ordering of all the data writes.}(hjphhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjmubah}(h]h ]h"]h$]h&]uh1jvhjSubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hbarrierh]hbarrier}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hEIf this option is set, cache_flush commands are allowed to be issued.h]hEIf this option is set, cache_flush commands are allowed to be issued.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hfastbooth]hfastboot}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hThis option is used when a system wants to reduce mount time as much as possible, even though normal performance can be sacrificed.h]hThis option is used when a system wants to reduce mount time as much as possible, even though normal performance can be sacrificed.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(h extent_cacheh]h extent_cache}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hEnable an extent cache based on rb-tree, it can cache as many as extent which map between contiguous logical address and physical address per inode, resulting in increasing the cache hit ratio. Set by default.h]hEnable an extent cache based on rb-tree, it can cache as many as extent which map between contiguous logical address and physical address per inode, resulting in increasing the cache hit ratio. Set by default.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hnoextent_cacheh]hnoextent_cache}(hj5 hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj2 ubah}(h]h ]h"]h$]h&]uh1jvhj/ ubjw)}(hhh]h)}(h]Disable an extent cache based on rb-tree explicitly, see the above extent_cache mount option.h]h]Disable an extent cache based on rb-tree explicitly, see the above extent_cache mount option.}(hjL hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjI ubah}(h]h ]h"]h$]h&]uh1jvhj/ ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(h noinline_datah]h noinline_data}(hjl hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhji ubah}(h]h ]h"]h$]h&]uh1jvhjf ubjw)}(hhh]h)}(hKDisable the inline data feature, inline data feature is enabled by default.h]hKDisable the inline data feature, inline data feature is enabled by default.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jvhjf ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(h data_flushh]h data_flush}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jvhj ubjw)}(hhh]h)}(hWEnable data flushing before checkpoint in order to persist data of regular and symlink.h]hWEnable data flushing before checkpoint in order to persist data of regular and symlink.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jvhj ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hreserve_root=%dh]hreserve_root=%d}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jvhj ubjw)}(hhh]h)}(hSupport configuring reserved space which is used for allocation from a privileged user with specified uid or gid, unit: 4KB, the default limit is 12.5% of user blocks.h]hSupport configuring reserved space which is used for allocation from a privileged user with specified uid or gid, unit: 4KB, the default limit is 12.5% of user blocks.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jvhj ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hreserve_node=%dh]hreserve_node=%d}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jvhj ubjw)}(hhh]h)}(hSupport configuring reserved nodes which are used for allocation from a privileged user with specified uid or gid, the default limit is 12.5% of all nodes.h]hSupport configuring reserved nodes which are used for allocation from a privileged user with specified uid or gid, the default limit is 12.5% of all nodes.}(hj( hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj% ubah}(h]h ]h"]h$]h&]uh1jvhj ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(h resuid=%dh]h resuid=%d}(hjH hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjE ubah}(h]h ]h"]h$]h&]uh1jvhjB ubjw)}(hhh]h)}(h8The user ID which may use the reserved blocks and nodes.h]h8The user ID which may use the reserved blocks and nodes.}(hj_ hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj\ ubah}(h]h ]h"]h$]h&]uh1jvhjB ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(h resgid=%dh]h resgid=%d}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj| ubah}(h]h ]h"]h$]h&]uh1jvhjy ubjw)}(hhh]h)}(h9The group ID which may use the reserved blocks and nodes.h]h9The group ID which may use the reserved blocks and nodes.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jvhjy ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hfault_injection=%dh]hfault_injection=%d}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jvhj ubjw)}(hhh]h)}(hLEnable fault injection in all supported types with specified injection rate.h]hLEnable fault injection in all supported types with specified injection rate.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jvhj ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(h fault_type=%dh]h fault_type=%d}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jvhj ubjw)}(hhh](h)}(hSupport configuring fault injection type, should be enabled with fault_injection option, fault type value is shown below, it supports single or combined type.h]hSupport configuring fault injection type, should be enabled with fault_injection option, fault type value is shown below, it supports single or combined type.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubh literal_block)}(hXO=========================== ========== Type_Name Type_Value =========================== ========== FAULT_KMALLOC 0x00000001 FAULT_KVMALLOC 0x00000002 FAULT_PAGE_ALLOC 0x00000004 FAULT_PAGE_GET 0x00000008 FAULT_ALLOC_BIO 0x00000010 (obsolete) FAULT_ALLOC_NID 0x00000020 FAULT_ORPHAN 0x00000040 FAULT_BLOCK 0x00000080 FAULT_DIR_DEPTH 0x00000100 FAULT_EVICT_INODE 0x00000200 FAULT_TRUNCATE 0x00000400 FAULT_READ_IO 0x00000800 FAULT_CHECKPOINT 0x00001000 FAULT_DISCARD 0x00002000 (obsolete) FAULT_WRITE_IO 0x00004000 FAULT_SLAB_ALLOC 0x00008000 FAULT_DQUOT_INIT 0x00010000 FAULT_LOCK_OP 0x00020000 FAULT_BLKADDR_VALIDITY 0x00040000 FAULT_BLKADDR_CONSISTENCE 0x00080000 FAULT_NO_SEGMENT 0x00100000 FAULT_INCONSISTENT_FOOTER 0x00200000 FAULT_ATOMIC_TIMEOUT 0x00400000 (1000ms) FAULT_VMALLOC 0x00800000 FAULT_LOCK_TIMEOUT 0x01000000 (1000ms) FAULT_SKIP_WRITE 0x02000000 =========================== ==========h]hXO=========================== ========== Type_Name Type_Value =========================== ========== FAULT_KMALLOC 0x00000001 FAULT_KVMALLOC 0x00000002 FAULT_PAGE_ALLOC 0x00000004 FAULT_PAGE_GET 0x00000008 FAULT_ALLOC_BIO 0x00000010 (obsolete) FAULT_ALLOC_NID 0x00000020 FAULT_ORPHAN 0x00000040 FAULT_BLOCK 0x00000080 FAULT_DIR_DEPTH 0x00000100 FAULT_EVICT_INODE 0x00000200 FAULT_TRUNCATE 0x00000400 FAULT_READ_IO 0x00000800 FAULT_CHECKPOINT 0x00001000 FAULT_DISCARD 0x00002000 (obsolete) FAULT_WRITE_IO 0x00004000 FAULT_SLAB_ALLOC 0x00008000 FAULT_DQUOT_INIT 0x00010000 FAULT_LOCK_OP 0x00020000 FAULT_BLKADDR_VALIDITY 0x00040000 FAULT_BLKADDR_CONSISTENCE 0x00080000 FAULT_NO_SEGMENT 0x00100000 FAULT_INCONSISTENT_FOOTER 0x00200000 FAULT_ATOMIC_TIMEOUT 0x00400000 (1000ms) FAULT_VMALLOC 0x00800000 FAULT_LOCK_TIMEOUT 0x01000000 (1000ms) FAULT_SKIP_WRITE 0x02000000 =========================== ==========}hj sbah}(h]h ]h"]h$]h&]hhƌforcelanguagenonehighlight_args}uh1j hhhKhj ubeh}(h]h ]h"]h$]h&]uh1jvhj ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hmode=%sh]hmode=%s}(hj9 hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj6 ubah}(h]h ]h"]h$]h&]uh1jvhj3 ubjw)}(hhh]h)}(hXControl block allocation mode which supports "adaptive" and "lfs". In "lfs" mode, there should be no random writes towards main area. "fragment:segment" and "fragment:block" are newly added here. These are developer options for experiments to simulate filesystem fragmentation/after-GC situation itself. The developers use these modes to understand filesystem fragmentation/after-GC condition well, and eventually get some insights to handle them better. In "fragment:segment", f2fs allocates a new segment in random position. With this, we can simulate the after-GC condition. In "fragment:block", we can scatter block allocation with "max_fragment_chunk" and "max_fragment_hole" sysfs nodes. We added some randomness to both chunk and hole size to make it close to realistic IO pattern. So, in this mode, f2fs will allocate 1.. blocks in a chunk and make a hole in the length of 1.. by turns. With this, the newly allocated blocks will be scattered throughout the whole partition. Note that "fragment:block" implicitly enables "fragment:segment" option for more randomness. Please, use these options for your experiments and we strongly recommend to re-format the filesystem after using these options.h]hXControl block allocation mode which supports “adaptive” and “lfs”. In “lfs” mode, there should be no random writes towards main area. “fragment:segment” and “fragment:block” are newly added here. These are developer options for experiments to simulate filesystem fragmentation/after-GC situation itself. The developers use these modes to understand filesystem fragmentation/after-GC condition well, and eventually get some insights to handle them better. In “fragment:segment”, f2fs allocates a new segment in random position. With this, we can simulate the after-GC condition. In “fragment:block”, we can scatter block allocation with “max_fragment_chunk” and “max_fragment_hole” sysfs nodes. We added some randomness to both chunk and hole size to make it close to realistic IO pattern. So, in this mode, f2fs will allocate 1.. blocks in a chunk and make a hole in the length of 1.. by turns. With this, the newly allocated blocks will be scattered throughout the whole partition. Note that “fragment:block” implicitly enables “fragment:segment” option for more randomness. Please, use these options for your experiments and we strongly recommend to re-format the filesystem after using these options.}(hjP hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjM ubah}(h]h ]h"]h$]h&]uh1jvhj3 ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(husrquotah]husrquota}(hjp hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhjm ubah}(h]h ]h"]h$]h&]uh1jvhjj ubjw)}(hhh]h)}(h(Enable plain user disk quota accounting.h]h(Enable plain user disk quota accounting.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jvhjj ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hgrpquotah]hgrpquota}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jvhj ubjw)}(hhh]h)}(h)Enable plain group disk quota accounting.h]h)Enable plain group disk quota accounting.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jvhj ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hprjquotah]hprjquota}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jvhj ubjw)}(hhh]h)}(h&Enable plain project quota accounting.h]h&Enable plain project quota accounting.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhKhj ubah}(h]h ]h"]h$]h&]uh1jvhj ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(husrjquota=h]husrjquota=}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj ubah}(h]h ]h"]h$]h&]uh1jvhj ubjw)}(hhh]h)}(h;Appoint specified file and type during mount, so that quotah]h;Appoint specified file and type during mount, so that quota}(hj, hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj) ubah}(h]h ]h"]h$]h&]uh1jvhj ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hgrpjquota=h]hgrpjquota=}(hjL hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjI ubah}(h]h ]h"]h$]h&]uh1jvhjF ubjw)}(hhh]h)}(h9information can be properly updated during recovery flow,h]h9information can be properly updated during recovery flow,}(hjc hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj` ubah}(h]h ]h"]h$]h&]uh1jvhjF ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hprjjquota=h]hprjjquota=}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj ubah}(h]h ]h"]h$]h&]uh1jvhj} ubjw)}(hhh]h)}(h(: must be in root directory;h]h(: must be in root directory;}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj ubah}(h]h ]h"]h$]h&]uh1jvhj} ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hjqfmt=h]hjqfmt=}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj ubah}(h]h ]h"]h$]h&]uh1jvhj ubjw)}(hhh]h)}(h#: [vfsold,vfsv0,vfsv1].h]h#: [vfsold,vfsv0,vfsv1].}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj ubah}(h]h ]h"]h$]h&]uh1jvhj ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(h usrjquota=h]h usrjquota=}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj ubah}(h]h ]h"]h$]h&]uh1jvhj ubjw)}(hhh]h)}(hTurn off user journalled quota.h]hTurn off user journalled quota.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj ubah}(h]h ]h"]h$]h&]uh1jvhj ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(h grpjquota=h]h grpjquota=}(hj( hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj% ubah}(h]h ]h"]h$]h&]uh1jvhj" ubjw)}(hhh]h)}(h Turn off group journalled quota.h]h Turn off group journalled quota.}(hj? hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj< ubah}(h]h ]h"]h$]h&]uh1jvhj" ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(h prjjquota=h]h prjjquota=}(hj_ hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj\ ubah}(h]h ]h"]h$]h&]uh1jvhjY ubjw)}(hhh]h)}(h"Turn off project journalled quota.h]h"Turn off project journalled quota.}(hjv hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjs ubah}(h]h ]h"]h$]h&]uh1jvhjY ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hquotah]hquota}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj ubah}(h]h ]h"]h$]h&]uh1jvhj ubjw)}(hhh]h)}(h(Enable plain user disk quota accounting.h]h(Enable plain user disk quota accounting.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj ubah}(h]h ]h"]h$]h&]uh1jvhj ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hnoquotah]hnoquota}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj ubah}(h]h ]h"]h$]h&]uh1jvhj ubjw)}(hhh]h)}(h$Disable all plain disk quota option.h]h$Disable all plain disk quota option.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj ubah}(h]h ]h"]h$]h&]uh1jvhj ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(h alloc_mode=%sh]h alloc_mode=%s}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM hjubah}(h]h ]h"]h$]h&]uh1jvhj ubjw)}(hhh]h)}(hEAdjust block allocation policy, which supports "reuse" and "default".h]hMAdjust block allocation policy, which supports “reuse” and “default”.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM hjubah}(h]h ]h"]h$]h&]uh1jvhj ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(h fsync_mode=%sh]h fsync_mode=%s}(hj;hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM hj8ubah}(h]h ]h"]h$]h&]uh1jvhj5ubjw)}(hhh]h)}(hXControl the policy of fsync. Currently supports "posix", "strict", and "nobarrier". In "posix" mode, which is default, fsync will follow POSIX semantics and does a light operation to improve the filesystem performance. In "strict" mode, fsync will be heavy and behaves in line with xfs, ext4 and btrfs, where xfstest generic/342 will pass, but the performance will regress. "nobarrier" is based on "posix", but doesn't issue flush command for non-atomic files likewise "nobarrier" mount option.h]hXControl the policy of fsync. Currently supports “posix”, “strict”, and “nobarrier”. In “posix” mode, which is default, fsync will follow POSIX semantics and does a light operation to improve the filesystem performance. In “strict” mode, fsync will be heavy and behaves in line with xfs, ext4 and btrfs, where xfstest generic/342 will pass, but the performance will regress. “nobarrier” is based on “posix”, but doesn’t issue flush command for non-atomic files likewise “nobarrier” mount option.}(hjRhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM hjOubah}(h]h ]h"]h$]h&]uh1jvhj5ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(htest_dummy_encryptionh]htest_dummy_encryption}(hjrhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjoubah}(h]h ]h"]h$]h&]uh1jvhjlubjw)}(hhh]h}(h]h ]h"]h$]h&]uh1jvhjlubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(htest_dummy_encryption=%sh]htest_dummy_encryption=%s}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hEnable dummy encryption, which provides a fake fscrypt context. The fake fscrypt context is used by xfstests. The argument may be either "v1" or "v2", in order to select the corresponding fscrypt policy version.h]hEnable dummy encryption, which provides a fake fscrypt context. The fake fscrypt context is used by xfstests. The argument may be either “v1” or “v2”, in order to select the corresponding fscrypt policy version.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hcheckpoint=%s[:%u[%]]h]hcheckpoint=%s[:%u[%]]}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hXSet to "disable" to turn off checkpointing. Set to "enable" to re-enable checkpointing. Is enabled by default. While disabled, any unmounting or unexpected shutdowns will cause the filesystem contents to appear as they did when the filesystem was mounted with that option. While mounting with checkpoint=disable, the filesystem must run garbage collection to ensure that all available space can be used. If this takes too much time, the mount may return EAGAIN. You may optionally add a value to indicate how much of the disk you would be willing to temporarily give up to avoid additional garbage collection. This can be given as a number of blocks, or as a percent. For instance, mounting with checkpoint=disable:100% would always succeed, but it may hide up to all remaining free space. The actual space that would be unusable can be viewed at /sys/fs/f2fs//unusable This space is reclaimed once checkpoint=enable.h]hXSet to “disable” to turn off checkpointing. Set to “enable” to re-enable checkpointing. Is enabled by default. While disabled, any unmounting or unexpected shutdowns will cause the filesystem contents to appear as they did when the filesystem was mounted with that option. While mounting with checkpoint=disable, the filesystem must run garbage collection to ensure that all available space can be used. If this takes too much time, the mount may return EAGAIN. You may optionally add a value to indicate how much of the disk you would be willing to temporarily give up to avoid additional garbage collection. This can be given as a number of blocks, or as a percent. For instance, mounting with checkpoint=disable:100% would always succeed, but it may hide up to all remaining free space. The actual space that would be unusable can be viewed at /sys/fs/f2fs//unusable This space is reclaimed once checkpoint=enable.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hcheckpoint_mergeh]hcheckpoint_merge}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM*hjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hXSWhen checkpoint is enabled, this can be used to create a kernel daemon and make it to merge concurrent checkpoint requests as much as possible to eliminate redundant checkpoint issues. Plus, we can eliminate the sluggish issue caused by slow checkpoint operation when the checkpoint is done in a process context in a cgroup having low i/o budget and cpu shares. To make this do better, we set the default i/o priority of the kernel daemon to "3", to give one higher priority than other kernel threads. This is the same way to give a I/O priority to the jbd2 journaling thread of ext4 filesystem.h]hXWWhen checkpoint is enabled, this can be used to create a kernel daemon and make it to merge concurrent checkpoint requests as much as possible to eliminate redundant checkpoint issues. Plus, we can eliminate the sluggish issue caused by slow checkpoint operation when the checkpoint is done in a process context in a cgroup having low i/o budget and cpu shares. To make this do better, we set the default i/o priority of the kernel daemon to “3”, to give one higher priority than other kernel threads. This is the same way to give a I/O priority to the jbd2 journaling thread of ext4 filesystem.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM*hjubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hnocheckpoint_mergeh]hnocheckpoint_merge}(hj@hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM4hj=ubah}(h]h ]h"]h$]h&]uh1jvhj:ubjw)}(hhh]h)}(h!Disable checkpoint merge feature.h]h!Disable checkpoint merge feature.}(hjWhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM4hjTubah}(h]h ]h"]h$]h&]uh1jvhj:ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hcompress_algorithm=%sh]hcompress_algorithm=%s}(hjwhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM5hjtubah}(h]h ]h"]h$]h&]uh1jvhjqubjw)}(hhh]h)}(haControl compress algorithm, currently f2fs supports "lzo", "lz4", "zstd" and "lzo-rle" algorithm.h]hqControl compress algorithm, currently f2fs supports “lzo”, “lz4”, “zstd” and “lzo-rle” algorithm.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM5hjubah}(h]h ]h"]h$]h&]uh1jvhjqubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hcompress_algorithm=%s:%dh]hcompress_algorithm=%s:%d}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM7hjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh](h)}(hmControl compress algorithm and its compress level, now, only "lz4" and "zstd" support compress level config::h]htControl compress algorithm and its compress level, now, only “lz4” and “zstd” support compress level config:}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM7hjubj )}(h========= =========== algorithm level range ========= =========== lz4 3 - 16 zstd 1 - 22 ========= ===========h]h========= =========== algorithm level range ========= =========== lz4 3 - 16 zstd 1 - 22 ========= ===========}hjsbah}(h]h ]h"]h$]h&]hhuh1j hhhM:hjubeh}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hcompress_log_size=%uh]hcompress_log_size=%u}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMAhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(htSupport configuring compress cluster size. The size will be 4KB * (1 << %u). The default and minimum sizes are 16KB.h]htSupport configuring compress cluster size. The size will be 4KB * (1 << %u). The default and minimum sizes are 16KB.}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMAhjubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hcompress_extension=%sh]hcompress_extension=%s}(hj*hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMChj'ubah}(h]h ]h"]h$]h&]uh1jvhj$ubjw)}(hhh]h)}(hXSupport adding specified extension, so that f2fs can enable compression on those corresponding files, e.g. if all files with '.ext' has high compression rate, we can set the '.ext' on compression extension list and enable compression on these file by default rather than to enable it via ioctl. For other files, we can still enable compression via ioctl. Note that, there is one reserved special extension '*', it can be set to enable compression for all files.h]hXSupport adding specified extension, so that f2fs can enable compression on those corresponding files, e.g. if all files with ‘.ext’ has high compression rate, we can set the ‘.ext’ on compression extension list and enable compression on these file by default rather than to enable it via ioctl. For other files, we can still enable compression via ioctl. Note that, there is one reserved special extension ‘*’, it can be set to enable compression for all files.}(hjAhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMChj>ubah}(h]h ]h"]h$]h&]uh1jvhj$ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hnocompress_extension=%sh]hnocompress_extension=%s}(hjahhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMKhj^ubah}(h]h ]h"]h$]h&]uh1jvhj[ubjw)}(hhh]h)}(hXSupport adding specified extension, so that f2fs can disable compression on those corresponding files, just contrary to compression extension. If you know exactly which files cannot be compressed, you can use this. The same extension name can't appear in both compress and nocompress extension at the same time. If the compress extension specifies all files, the types specified by the nocompress extension will be treated as special cases and will not be compressed. Don't allow use '*' to specifie all file in nocompress extension. After add nocompress_extension, the priority should be: dir_flag < comp_extention,nocompress_extension < comp_file_flag,no_comp_file_flag. See more in compression sections.h]hXSupport adding specified extension, so that f2fs can disable compression on those corresponding files, just contrary to compression extension. If you know exactly which files cannot be compressed, you can use this. The same extension name can’t appear in both compress and nocompress extension at the same time. If the compress extension specifies all files, the types specified by the nocompress extension will be treated as special cases and will not be compressed. Don’t allow use ‘*’ to specifie all file in nocompress extension. After add nocompress_extension, the priority should be: dir_flag < comp_extention,nocompress_extension < comp_file_flag,no_comp_file_flag. See more in compression sections.}(hjxhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMKhjuubah}(h]h ]h"]h$]h&]uh1jvhj[ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hcompress_chksumh]hcompress_chksum}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMWhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(h;Support verifying chksum of raw data in compressed cluster.h]h;Support verifying chksum of raw data in compressed cluster.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMWhjubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hcompress_mode=%sh]hcompress_mode=%s}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMXhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hX~Control file compression mode. This supports "fs" and "user" modes. In "fs" mode (default), f2fs does automatic compression on the compression enabled files. In "user" mode, f2fs disables the automaic compression and gives the user discretion of choosing the target file and the timing. The user can do manual compression/decompression on the compression enabled files using ioctls.h]hXControl file compression mode. This supports “fs” and “user” modes. In “fs” mode (default), f2fs does automatic compression on the compression enabled files. In “user” mode, f2fs disables the automaic compression and gives the user discretion of choosing the target file and the timing. The user can do manual compression/decompression on the compression enabled files using ioctls.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMXhjubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hcompress_cacheh]hcompress_cache}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM_hjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hSupport to use address space of a filesystem managed inode to cache compressed block, in order to improve cache hit ratio of random read.h]hSupport to use address space of a filesystem managed inode to cache compressed block, in order to improve cache hit ratio of random read.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM_hjubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(h inlinecrypth]h inlinecrypt}(hj=hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMbhj:ubah}(h]h ]h"]h$]h&]uh1jvhj7ubjw)}(hhh]h)}(hWhen possible, encrypt/decrypt the contents of encrypted files using inline encryption hardware rather than the CPU. For more details, see Documentation/filesystems/fscrypt.rst.h]hWhen possible, encrypt/decrypt the contents of encrypted files using inline encryption hardware rather than the CPU. For more details, see Documentation/filesystems/fscrypt.rst.}(hjThhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMbhjQubah}(h]h ]h"]h$]h&]uh1jvhj7ubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hatgch]hatgc}(hjthhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMfhjqubah}(h]h ]h"]h$]h&]uh1jvhjnubjw)}(hhh]h)}(hhEnable age-threshold garbage collection, it provides high effectiveness and efficiency on background GC.h]hhEnable age-threshold garbage collection, it provides high effectiveness and efficiency on background GC.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMfhjubah}(h]h ]h"]h$]h&]uh1jvhjnubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hdiscard_unit=%sh]hdiscard_unit=%s}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hXControl discard unit, the argument can be "block", "segment" and "section", issued discard command's offset/size will be aligned to the unit, by default, "discard_unit=block" is set, so that small discard functionality is enabled. For blkzoned device, "discard_unit=section" will be set by default, it is helpful for large sized SMR or ZNS devices to reduce memory cost by getting rid of fs metadata supports small discard.h]hXControl discard unit, the argument can be “block”, “segment” and “section”, issued discard command’s offset/size will be aligned to the unit, by default, “discard_unit=block” is set, so that small discard functionality is enabled. For blkzoned device, “discard_unit=section” will be set by default, it is helpful for large sized SMR or ZNS devices to reduce memory cost by getting rid of fs metadata supports small discard.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhhjubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(h memory=%sh]h memory=%s}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMphjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hX(Control memory mode. This supports "normal" and "low" modes. "low" mode is introduced to support low memory devices. Because of the nature of low memory devices, in this mode, f2fs will try to save memory sometimes by sacrificing performance. "normal" mode is the default mode and same as before.h]hX8Control memory mode. This supports “normal” and “low” modes. “low” mode is introduced to support low memory devices. Because of the nature of low memory devices, in this mode, f2fs will try to save memory sometimes by sacrificing performance. “normal” mode is the default mode and same as before.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMphjubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hage_extent_cacheh]hage_extent_cache}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMuhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hEnable an age extent cache based on rb-tree. It records data block update frequency of the extent per inode, in order to provide better temperature hints for data block allocation.h]hEnable an age extent cache based on rb-tree. It records data block update frequency of the extent per inode, in order to provide better temperature hints for data block allocation.}(hj0hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMuhj-ubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(h errors=%sh]h errors=%s}(hjPhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMyhjMubah}(h]h ]h"]h$]h&]uh1jvhjJubjw)}(hhh](h)}(hSpecify f2fs behavior on critical errors. This supports modes: "panic", "continue" and "remount-ro", respectively, trigger panic immediately, continue without doing anything, and remount the partition in read-only mode. By default it uses "continue" mode.h]hXSpecify f2fs behavior on critical errors. This supports modes: “panic”, “continue” and “remount-ro”, respectively, trigger panic immediately, continue without doing anything, and remount the partition in read-only mode. By default it uses “continue” mode.}(hjghhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMyhjdubj )}(hX====================== =============== =============== ======== mode continue remount-ro panic ====================== =============== =============== ======== access ops normal normal N/A syscall errors -EIO -EROFS N/A mount option rw ro N/A pending dir write keep keep N/A pending non-dir write drop keep N/A pending node write drop keep N/A pending meta write keep keep N/A ====================== =============== =============== ========h]hX====================== =============== =============== ======== mode continue remount-ro panic ====================== =============== =============== ======== access ops normal normal N/A syscall errors -EIO -EROFS N/A mount option rw ro N/A pending dir write keep keep N/A pending non-dir write drop keep N/A pending node write drop keep N/A pending meta write keep keep N/A ====================== =============== =============== ========}hjusbah}(h]h ]h"]h$]h&]hhj" j# nonej% }uh1j hhhMhjdubeh}(h]h ]h"]h$]h&]uh1jvhjJubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hnat_bitsh]hnat_bits}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hZEnable nat_bits feature to enhance full/empty nat blocks access, by default it's disabled.h]h\Enable nat_bits feature to enhance full/empty nat blocks access, by default it’s disabled.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hlookup_mode=%sh]hlookup_mode=%s}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh](h)}(hControl the directory lookup behavior for casefolded directories. This option has no effect on directories that do not have the casefold feature enabled.h]hControl the directory lookup behavior for casefolded directories. This option has no effect on directories that do not have the casefold feature enabled.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjubj )}(hX================== ======================================== Value Description ================== ======================================== perf (Default) Enforces a hash-only lookup. The linear search fallback is always disabled, ignoring the on-disk flag. compat Enables the linear search fallback for compatibility with directory entries created by older kernel that used a different case-folding algorithm. This mode ignores the on-disk flag. auto F2FS determines the mode based on the on-disk `SB_ENC_NO_COMPAT_FALLBACK_FL` flag.h]hX================== ======================================== Value Description ================== ======================================== perf (Default) Enforces a hash-only lookup. The linear search fallback is always disabled, ignoring the on-disk flag. compat Enables the linear search fallback for compatibility with directory entries created by older kernel that used a different case-folding algorithm. This mode ignores the on-disk flag. auto F2FS determines the mode based on the on-disk `SB_ENC_NO_COMPAT_FALLBACK_FL` flag.}hjsbah}(h]h ]h"]h$]h&]hhj" j# nonej% }uh1j hhhMhjubeh}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubjr)}(hhh](jw)}(hhh]h)}(hresizable_tail_secno=%uh]hresizable_tail_secno=%u}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hX9Control the number of sections at the tail of the filesystem reserved for online resizing. Pinned files will only be allocated within sections 0 to (MAIN_SECS - resizable_tail_secno) - 1. If set to 0 (default), there is no tail restriction unless running on a zoned block device where conventional zones are used.h]hX9Control the number of sections at the tail of the filesystem reserved for online resizing. Pinned files will only be allocated within sections 0 to (MAIN_SECS - resizable_tail_secno) - 1. If set to 0 (default), there is no tail restriction unless running on a zoned block device where conventional zones are used.}(hj,hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj)ubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjnubeh}(h]h ]h"]h$]h&]uh1jlhjSubeh}(h]h ]h"]h$]h&]colsKuh1jQhjNubah}(h]h ]h"]h$]h&]uh1jLhj;hhhhhNubeh}(h] mount-optionsah ]h"] mount optionsah$]h&]uh1hhhhhhhhKlubh)}(hhh](h)}(hDebugfs Entriesh]hDebugfs Entries}(hjdhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjahhhhhMubh)}(h/sys/kernel/debug/f2fs/ contains information about all the partitions mounted as f2fs. Each file shows the whole f2fs information.h]h/sys/kernel/debug/f2fs/ contains information about all the partitions mounted as f2fs. Each file shows the whole f2fs information.}(hjrhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjahhubh)}(h'/sys/kernel/debug/f2fs/status includes:h]h'/sys/kernel/debug/f2fs/status includes:}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjahhubh block_quote)}(h- major file system information managed by f2fs currently - average SIT information about whole segments - current memory footprint consumed by f2fs. h]j))}(hhh](j.)}(h7major file system information managed by f2fs currentlyh]h)}(hjh]h7major file system information managed by f2fs currently}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjubah}(h]h ]h"]h$]h&]uh1j-hjubj.)}(h,average SIT information about whole segmentsh]h)}(hjh]h,average SIT information about whole segments}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjubah}(h]h ]h"]h$]h&]uh1j-hjubj.)}(h+current memory footprint consumed by f2fs. h]h)}(h*current memory footprint consumed by f2fs.h]h*current memory footprint consumed by f2fs.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjubah}(h]h ]h"]h$]h&]uh1j-hjubeh}(h]h ]h"]h$]h&]jMjNuh1j(hhhMhjubah}(h]h ]h"]h$]h&]uh1jhhhMhjahhubeh}(h]debugfs-entriesah ]h"]debugfs entriesah$]h&]uh1hhhhhhhhMubh)}(hhh](h)}(h Sysfs Entriesh]h Sysfs Entries}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjhhhhhMubh)}(hInformation about mounted f2fs file systems can be found in /sys/fs/f2fs. Each mounted filesystem will have a directory in /sys/fs/f2fs based on its device name (i.e., /sys/fs/f2fs/sda). The files in each per-device directory are shown in table below.h]hInformation about mounted f2fs file systems can be found in /sys/fs/f2fs. Each mounted filesystem will have a directory in /sys/fs/f2fs based on its device name (i.e., /sys/fs/f2fs/sda). The files in each per-device directory are shown in table below.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjhhubh)}(hRFiles in /sys/fs/f2fs/ (see also Documentation/ABI/testing/sysfs-fs-f2fs)h]hRFiles in /sys/fs/f2fs/ (see also Documentation/ABI/testing/sysfs-fs-f2fs)}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjhhubeh}(h] sysfs-entriesah ]h"] sysfs entriesah$]h&]uh1hhhhhhhhMubh)}(hhh](h)}(hUsageh]hUsage}(hj)hhhNhNubah}(h]h ]h"]h$]h&]uh1hhj&hhhhhMubjw)}(hhh](j.)}(h*Download userland tools and compile them. h]h)}(h)Download userland tools and compile them.h]h)Download userland tools and compile them.}(hj>hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj:ubah}(h]h ]h"]h$]h&]uh1j-hj7hhhhhNubj.)}(hsSkip, if f2fs was compiled statically inside kernel. Otherwise, insert the f2fs.ko module:: # insmod f2fs.ko h](h)}(h[Skip, if f2fs was compiled statically inside kernel. Otherwise, insert the f2fs.ko module::h]hZSkip, if f2fs was compiled statically inside kernel. Otherwise, insert the f2fs.ko module:}(hjVhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjRubj )}(h# insmod f2fs.koh]h# insmod f2fs.ko}hjdsbah}(h]h ]h"]h$]h&]hhuh1j hhhMhjRubeh}(h]h ]h"]h$]h&]uh1j-hj7hhhhhNubj.)}(hBCreate a directory to use when mounting:: # mkdir /mnt/f2fs h](h)}(h)Create a directory to use when mounting::h]h(Create a directory to use when mounting:}(hj|hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjxubj )}(h# mkdir /mnt/f2fsh]h# mkdir /mnt/f2fs}hjsbah}(h]h ]h"]h$]h&]hhuh1j hhhMhjxubeh}(h]h ]h"]h$]h&]uh1j-hj7hhhhhNubj.)}(hFormat the block device, and then mount as f2fs:: # mkfs.f2fs -l label /dev/block_device # mount -t f2fs /dev/block_device /mnt/f2fs h](h)}(h1Format the block device, and then mount as f2fs::h]h0Format the block device, and then mount as f2fs:}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjubj )}(hR# mkfs.f2fs -l label /dev/block_device # mount -t f2fs /dev/block_device /mnt/f2fsh]hR# mkfs.f2fs -l label /dev/block_device # mount -t f2fs /dev/block_device /mnt/f2fs}hjsbah}(h]h ]h"]h$]h&]hhuh1j hhhMhjubeh}(h]h ]h"]h$]h&]uh1j-hj7hhhhhNubeh}(h]h ]h"]h$]h&]jjjhjjuh1jvhj&hhhhhMubh)}(hhh](h)}(h mkfs.f2fsh]h mkfs.f2fs}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjhhhhhMubh)}(hsThe mkfs.f2fs is for the use of formatting a partition as the f2fs filesystem, which builds a basic on-disk layout.h]hsThe mkfs.f2fs is for the use of formatting a partition as the f2fs filesystem, which builds a basic on-disk layout.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjhhubh)}(hThe quick options consist of:h]hThe quick options consist of:}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjhhubjM)}(hhh]jR)}(hhh](jW)}(hhh]h}(h]h ]h"]h$]h&]colwidthKuh1jVhjubjW)}(hhh]h}(h]h ]h"]h$]h&]colwidthK align with the segment size _________________________________________________________________________ | | | Segment | Node | Segment | | | Superblock | Checkpoint | Info. | Address | Summary | Main | | (SB) | (CP) | Table (SIT) | Table (NAT) | Area (SSA) | | |____________|_____2______|______N______|______N______|______N_____|__N___| . . . . . . ._________________________________________. |_Segment_|_..._|_Segment_|_..._|_Segment_| . . ._________._________ |_section_|__...__|_ . . .________. |__zone__|h]hX align with the zone size <-| |-> align with the segment size _________________________________________________________________________ | | | Segment | Node | Segment | | | Superblock | Checkpoint | Info. | Address | Summary | Main | | (SB) | (CP) | Table (SIT) | Table (NAT) | Area (SSA) | | |____________|_____2______|______N______|______N______|______N_____|__N___| . . . . . . ._________________________________________. |_Segment_|_..._|_Segment_|_..._|_Segment_| . . ._________._________ |_section_|__...__|_ . . .________. |__zone__|}hj+sbah}(h]h ]h"]h$]h&]hhuh1j hhhMChjhhubj))}(hhh](j.)}(hSuperblock (SB) It is located at the beginning of the partition, and there exist two copies to avoid file system crash. It contains basic partition information and some default parameters of f2fs. h]hdefinition_list)}(hhh]hdefinition_list_item)}(hSuperblock (SB) It is located at the beginning of the partition, and there exist two copies to avoid file system crash. It contains basic partition information and some default parameters of f2fs. h](hterm)}(hSuperblock (SB)h]hSuperblock (SB)}(hjMhhhNhNubah}(h]h ]h"]h$]h&]uh1jKhhhMYhjGubh definition)}(hhh]h)}(hIt is located at the beginning of the partition, and there exist two copies to avoid file system crash. It contains basic partition information and some default parameters of f2fs.h]hIt is located at the beginning of the partition, and there exist two copies to avoid file system crash. It contains basic partition information and some default parameters of f2fs.}(hj`hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMWhj]ubah}(h]h ]h"]h$]h&]uh1j[hjGubeh}(h]h ]h"]h$]h&]uh1jEhhhMYhjBubah}(h]h ]h"]h$]h&]uh1j@hj<ubah}(h]h ]h"]h$]h&]uh1j-hj9hhhNhNubj.)}(hCheckpoint (CP) It contains file system information, bitmaps for valid NAT/SIT sets, orphan inode lists, and summary entries of current active segments. h]jA)}(hhh]jF)}(hCheckpoint (CP) It contains file system information, bitmaps for valid NAT/SIT sets, orphan inode lists, and summary entries of current active segments. h](jL)}(hCheckpoint (CP)h]hCheckpoint (CP)}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jKhhhM]hjubj\)}(hhh]h)}(hIt contains file system information, bitmaps for valid NAT/SIT sets, orphan inode lists, and summary entries of current active segments.h]hIt contains file system information, bitmaps for valid NAT/SIT sets, orphan inode lists, and summary entries of current active segments.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM\hjubah}(h]h ]h"]h$]h&]uh1j[hjubeh}(h]h ]h"]h$]h&]uh1jEhhhM]hjubah}(h]h ]h"]h$]h&]uh1j@hjubah}(h]h ]h"]h$]h&]uh1j-hj9hhhNhNubj.)}(hSegment Information Table (SIT) It contains segment information such as valid block count and bitmap for the validity of all the blocks. h]jA)}(hhh]jF)}(hSegment Information Table (SIT) It contains segment information such as valid block count and bitmap for the validity of all the blocks. h](jL)}(hSegment Information Table (SIT)h]hSegment Information Table (SIT)}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jKhhhMahjubj\)}(hhh]h)}(hhIt contains segment information such as valid block count and bitmap for the validity of all the blocks.h]hhIt contains segment information such as valid block count and bitmap for the validity of all the blocks.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM`hjubah}(h]h ]h"]h$]h&]uh1j[hjubeh}(h]h ]h"]h$]h&]uh1jEhhhMahjubah}(h]h ]h"]h$]h&]uh1j@hjubah}(h]h ]h"]h$]h&]uh1j-hj9hhhNhNubj.)}(hpNode Address Table (NAT) It is composed of a block address table for all the node blocks stored in Main area. h]jA)}(hhh]jF)}(hnNode Address Table (NAT) It is composed of a block address table for all the node blocks stored in Main area. h](jL)}(hNode Address Table (NAT)h]hNode Address Table (NAT)}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jKhhhMehjubj\)}(hhh]h)}(hTIt is composed of a block address table for all the node blocks stored in Main area.h]hTIt is composed of a block address table for all the node blocks stored in Main area.}(hj&hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMdhj#ubah}(h]h ]h"]h$]h&]uh1j[hjubeh}(h]h ]h"]h$]h&]uh1jEhhhMehjubah}(h]h ]h"]h$]h&]uh1j@hj ubah}(h]h ]h"]h$]h&]uh1j-hj9hhhNhNubj.)}(hSegment Summary Area (SSA) It contains summary entries which contains the owner information of all the data and node blocks stored in Main area. h]jA)}(hhh]jF)}(hSegment Summary Area (SSA) It contains summary entries which contains the owner information of all the data and node blocks stored in Main area. h](jL)}(hSegment Summary Area (SSA)h]hSegment Summary Area (SSA)}(hjWhhhNhNubah}(h]h ]h"]h$]h&]uh1jKhhhMihjSubj\)}(hhh]h)}(huIt contains summary entries which contains the owner information of all the data and node blocks stored in Main area.h]huIt contains summary entries which contains the owner information of all the data and node blocks stored in Main area.}(hjhhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhhjeubah}(h]h ]h"]h$]h&]uh1j[hjSubeh}(h]h ]h"]h$]h&]uh1jEhhhMihjPubah}(h]h ]h"]h$]h&]uh1j@hjLubah}(h]h ]h"]h$]h&]uh1j-hj9hhhNhNubj.)}(hHMain Area It contains file and directory data including their indices. h]jA)}(hhh]jF)}(hGMain Area It contains file and directory data including their indices. h](jL)}(h Main Areah]h Main Area}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1jKhhhMlhjubj\)}(hhh]h)}(hsbah}(h]h ]h"]h$]h&]hhuh1j hhhMhjhhubh)}(h4The number of blocks and buckets are determined by::h]h3The number of blocks and buckets are determined by:}(hjLhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjhhubj )}(hX ,- 2, if n < MAX_DIR_HASH_DEPTH / 2, # of blocks in level #n = | `- 4, Otherwise ,- 2^(n + dir_level), | if n + dir_level < MAX_DIR_HASH_DEPTH / 2, # of buckets in level #n = | `- 2^((MAX_DIR_HASH_DEPTH / 2) - 1), Otherwiseh]hX ,- 2, if n < MAX_DIR_HASH_DEPTH / 2, # of blocks in level #n = | `- 4, Otherwise ,- 2^(n + dir_level), | if n + dir_level < MAX_DIR_HASH_DEPTH / 2, # of buckets in level #n = | `- 2^((MAX_DIR_HASH_DEPTH / 2) - 1), Otherwise}hjZsbah}(h]h ]h"]h$]h&]hhuh1j hhhMhjhhubh)}(hXWhen F2FS finds a file name in a directory, at first a hash value of the file name is calculated. Then, F2FS scans the hash table in level #0 to find the dentry consisting of the file name and its inode number. If not found, F2FS scans the next hash table in level #1. In this way, F2FS scans hash tables in each levels incrementally from 1 to N. In each level F2FS needs to scan only one bucket determined by the following equation, which shows O(log(# of files)) complexity::h]hXWhen F2FS finds a file name in a directory, at first a hash value of the file name is calculated. Then, F2FS scans the hash table in level #0 to find the dentry consisting of the file name and its inode number. If not found, F2FS scans the next hash table in level #1. In this way, F2FS scans hash tables in each levels incrementally from 1 to N. In each level F2FS needs to scan only one bucket determined by the following equation, which shows O(log(# of files)) complexity:}(hjhhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjhhubj )}(hMbucket number to scan in level #n = (hash value) % (# of buckets in level #n)h]hMbucket number to scan in level #n = (hash value) % (# of buckets in level #n)}hjvsbah}(h]h ]h"]h$]h&]hhuh1j hhhMhjhhubh)}(hIn the case of file creation, F2FS finds empty consecutive slots that cover the file name. F2FS searches the empty slots in the hash tables of whole levels from 1 to N in the same way as the lookup operation.h]hIn the case of file creation, F2FS finds empty consecutive slots that cover the file name. F2FS searches the empty slots in the hash tables of whole levels from 1 to N in the same way as the lookup operation.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjhhubh)}(hEThe following figure shows an example of two cases holding children::h]hDThe following figure shows an example of two cases holding children:}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjhhubj )}(hX| --------------> Dir <-------------- | | child child child - child [hole] - child child - child - child [hole] - [hole] - child Case 1: Case 2: Number of children = 6, Number of children = 3, File size = 7 File size = 7h]hX| --------------> Dir <-------------- | | child child child - child [hole] - child child - child - child [hole] - [hole] - child Case 1: Case 2: Number of children = 6, Number of children = 3, File size = 7 File size = 7}hjsbah}(h]h ]h"]h$]h&]hhuh1j hhhMhjhhubeh}(h]directory-structureah ]h"]directory structureah$]h&]uh1hhjhhhhhMubh)}(hhh](h)}(hDefault Block Allocationh]hDefault Block Allocation}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjhhhhhMubh)}(hgAt runtime, F2FS manages six active logs inside "Main" area: Hot/Warm/Cold node and Hot/Warm/Cold data.h]hkAt runtime, F2FS manages six active logs inside “Main” area: Hot/Warm/Cold node and Hot/Warm/Cold data.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjhhubj))}(hhh](j.)}(h9Hot node contains direct node blocks of directories.h]h)}(hjh]h9Hot node contains direct node blocks of directories.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjubah}(h]h ]h"]h$]h&]uh1j-hjhhhhhNubj.)}(hAWarm node contains direct node blocks except hot node blocks.h]h)}(hjh]hAWarm node contains direct node blocks except hot node blocks.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjubah}(h]h ]h"]h$]h&]uh1j-hjhhhhhNubj.)}(h+Cold node contains indirect node blocksh]h)}(hjh]h+Cold node contains indirect node blocks}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjubah}(h]h ]h"]h$]h&]uh1j-hjhhhhhNubj.)}(h$Hot data contains dentry blocksh]h)}(hjh]h$Hot data contains dentry blocks}(hj!hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjubah}(h]h ]h"]h$]h&]uh1j-hjhhhhhNubj.)}(hBWarm data contains data blocks except hot and cold data blocksh]h)}(hj6h]hBWarm data contains data blocks except hot and cold data blocks}(hj8hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj4ubah}(h]h ]h"]h$]h&]uh1j-hjhhhhhNubj.)}(h?Cold data contains multimedia data or migrated data blocks h]h)}(h>Cold data contains multimedia data or migrated data blocksh]h>Cold data contains multimedia data or migrated data blocks}(hjOhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjKubah}(h]h ]h"]h$]h&]uh1j-hjhhhhhNubeh}(h]h ]h"]h$]h&]jMjNuh1j(hhhMhjhhubh)}(hXLFS has two schemes for free space management: threaded log and copy-and-compac- tion. The copy-and-compaction scheme which is known as cleaning, is well-suited for devices showing very good sequential write performance, since free segments are served all the time for writing new data. However, it suffers from cleaning overhead under high utilization. Contrarily, the threaded log scheme suffers from random writes, but no cleaning process is needed. F2FS adopts a hybrid scheme where the copy-and-compaction scheme is adopted by default, but the policy is dynamically changed to the threaded log scheme according to the file system status.h]hXLFS has two schemes for free space management: threaded log and copy-and-compac- tion. The copy-and-compaction scheme which is known as cleaning, is well-suited for devices showing very good sequential write performance, since free segments are served all the time for writing new data. However, it suffers from cleaning overhead under high utilization. Contrarily, the threaded log scheme suffers from random writes, but no cleaning process is needed. F2FS adopts a hybrid scheme where the copy-and-compaction scheme is adopted by default, but the policy is dynamically changed to the threaded log scheme according to the file system status.}(hjihhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhjhhubh)}(hXIn order to align F2FS with underlying flash-based storage, F2FS allocates a segment in a unit of section. F2FS expects that the section size would be the same as the unit size of garbage collection in FTL. Furthermore, with respect to the mapping granularity in FTL, F2FS allocates each section of the active logs from different zones as much as possible, since FTL can write the data in the active logs into one allocation unit according to its mapping granularity.h]hXIn order to align F2FS with underlying flash-based storage, F2FS allocates a segment in a unit of section. F2FS expects that the section size would be the same as the unit size of garbage collection in FTL. Furthermore, with respect to the mapping granularity in FTL, F2FS allocates each section of the active logs from different zones as much as possible, since FTL can write the data in the active logs into one allocation unit according to its mapping granularity.}(hjwhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM'hjhhubeh}(h]default-block-allocationah ]h"]default block allocationah$]h&]uh1hhjhhhhhMubh)}(hhh](h)}(hCleaning processh]hCleaning process}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjhhhhhM/ubh)}(hF2FS does cleaning both on demand and in the background. On-demand cleaning is triggered when there are not enough free segments to serve VFS calls. Background cleaner is operated by a kernel thread, and triggers the cleaning job when the system is idle.h]hF2FS does cleaning both on demand and in the background. On-demand cleaning is triggered when there are not enough free segments to serve VFS calls. Background cleaner is operated by a kernel thread, and triggers the cleaning job when the system is idle.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM1hjhhubh)}(hXF2FS supports two victim selection policies: greedy and cost-benefit algorithms. In the greedy algorithm, F2FS selects a victim segment having the smallest number of valid blocks. In the cost-benefit algorithm, F2FS selects a victim segment according to the segment age and the number of valid blocks in order to address log block thrashing problem in the greedy algorithm. F2FS adopts the greedy algorithm for on-demand cleaner, while background cleaner adopts cost-benefit algorithm.h]hXF2FS supports two victim selection policies: greedy and cost-benefit algorithms. In the greedy algorithm, F2FS selects a victim segment having the smallest number of valid blocks. In the cost-benefit algorithm, F2FS selects a victim segment according to the segment age and the number of valid blocks in order to address log block thrashing problem in the greedy algorithm. F2FS adopts the greedy algorithm for on-demand cleaner, while background cleaner adopts cost-benefit algorithm.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM6hjhhubh)}(hIn order to identify whether the data in the victim segment are valid or not, F2FS manages a bitmap. Each bit represents the validity of a block, and the bitmap is composed of a bit stream covering whole blocks in main area.h]hIn order to identify whether the data in the victim segment are valid or not, F2FS manages a bitmap. Each bit represents the validity of a block, and the bitmap is composed of a bit stream covering whole blocks in main area.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM>hjhhubeh}(h]cleaning-processah ]h"]cleaning processah$]h&]uh1hhjhhhhhM/ubh)}(hhh](h)}(hWrite-hint Policyh]hWrite-hint Policy}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhjhhhhhMCubh)}(h7F2FS sets the whint all the time with the below policy.h]h7F2FS sets the whint all the time with the below policy.}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMEhjhhubjM)}(hhh]jR)}(hhh](jW)}(hhh]h}(h]h ]h"]h$]h&]colwidthKuh1jVhjubjW)}(hhh]h}(h]h ]h"]h$]h&]colwidthKuh1jVhjubjW)}(hhh]h}(h]h ]h"]h$]h&]colwidthKuh1jVhjubhthead)}(hhh]jr)}(hhh](jw)}(hhh]h)}(hUserh]hUser}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMHhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hF2FSh]hF2FS}(hj5hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMHhj2ubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hBlockh]hBlock}(hjLhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMHhjIubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjubah}(h]h ]h"]h$]h&]uh1jhjubjm)}(hhh](jr)}(hhh](jw)}(hhh]h)}(hN/Ah]hN/A}(hjuhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMJhjrubah}(h]h ]h"]h$]h&]uh1jvhjoubjw)}(hhh]h)}(hMETAh]hMETA}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMJhjubah}(h]h ]h"]h$]h&]uh1jvhjoubjw)}(hhh]h)}(hWRITE_LIFE_NONE|REQ_METAh]hWRITE_LIFE_NONE|REQ_META}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMJhjubah}(h]h ]h"]h$]h&]uh1jvhjoubeh}(h]h ]h"]h$]h&]uh1jqhjlubjr)}(hhh](jw)}(hhh]h)}(hN/Ah]hN/A}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMKhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hHOT_NODEh]hHOT_NODE}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMKhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hWRITE_LIFE_NONEh]hWRITE_LIFE_NONE}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMKhjubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjlubjr)}(hhh](jw)}(hhh]h)}(hN/Ah]hN/A}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMLhjubah}(h]h ]h"]h$]h&]uh1jvhj ubjw)}(hhh]h)}(h WARM_NODEh]h WARM_NODE}(hj(hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMLhj%ubah}(h]h ]h"]h$]h&]uh1jvhj ubjw)}(hhh]h)}(hWRITE_LIFE_MEDIUMh]hWRITE_LIFE_MEDIUM}(hj?hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMLhj<ubah}(h]h ]h"]h$]h&]uh1jvhj ubeh}(h]h ]h"]h$]h&]uh1jqhjlubjr)}(hhh](jw)}(hhh]h)}(hN/Ah]hN/A}(hj_hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMMhj\ubah}(h]h ]h"]h$]h&]uh1jvhjYubjw)}(hhh]h)}(h COLD_NODEh]h COLD_NODE}(hjvhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMMhjsubah}(h]h ]h"]h$]h&]uh1jvhjYubjw)}(hhh]h)}(hWRITE_LIFE_LONGh]hWRITE_LIFE_LONG}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMMhjubah}(h]h ]h"]h$]h&]uh1jvhjYubeh}(h]h ]h"]h$]h&]uh1jqhjlubjr)}(hhh](jw)}(hhh]h)}(h ioctl(COLD)h]h ioctl(COLD)}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMNhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(h COLD_DATAh]h COLD_DATA}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMNhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hWRITE_LIFE_EXTREMEh]hWRITE_LIFE_EXTREME}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMNhjubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjlubjr)}(hhh](jw)}(hhh]h)}(hextension listh]hextension list}(hjhhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMOhjubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(h"h]h“}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMOhj ubah}(h]h ]h"]h$]h&]uh1jvhjubjw)}(hhh]h)}(hj h]h“}(hj) hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMOhj& ubah}(h]h ]h"]h$]h&]uh1jvhjubeh}(h]h ]h"]h$]h&]uh1jqhjlubjr)}(hhh]jw)}(hhh]h)}(h-- buffered ioh]h-- buffered io}(hjH hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMQhjE ubah}(h]h ]h"]h$]h&]morecolsKuh1jvhjB ubah}(h]h ]h"]h$]h&]uh1jqhjlubjr)}(hhh](jw)}(hhh]h)}(hN/Ah]hN/A}(hji hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMShjf ubah}(h]h ]h"]h$]h&]uh1jvhjc ubjw)}(hhh]h)}(h COLD_DATAh]h COLD_DATA}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMShj} ubah}(h]h ]h"]h$]h&]uh1jvhjc ubjw)}(hhh]h)}(hWRITE_LIFE_EXTREMEh]hWRITE_LIFE_EXTREME}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMShj ubah}(h]h ]h"]h$]h&]uh1jvhjc ubeh}(h]h ]h"]h$]h&]uh1jqhjlubjr)}(hhh](jw)}(hhh]h)}(hN/Ah]hN/A}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMThj ubah}(h]h ]h"]h$]h&]uh1jvhj ubjw)}(hhh]h)}(hHOT_DATAh]hHOT_DATA}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMThj ubah}(h]h ]h"]h$]h&]uh1jvhj ubjw)}(hhh]h)}(hWRITE_LIFE_SHORTh]hWRITE_LIFE_SHORT}(hj hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMThj ubah}(h]h ]h"]h$]h&]uh1jvhj ubeh}(h]h ]h"]h$]h&]uh1jqhjlubjr)}(hhh](jw)}(hhh]h)}(hN/Ah]hN/A}(hj!hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMUhj!ubah}(h]h ]h"]h$]h&]uh1jvhj ubjw)}(hhh]h)}(h WARM_DATAh]h WARM_DATA}(hj!hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMUhj!ubah}(h]h ]h"]h$]h&]uh1jvhj ubjw)}(hhh]h)}(hWRITE_LIFE_NOT_SETh]hWRITE_LIFE_NOT_SET}(hj3!hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMUhj0!ubah}(h]h ]h"]h$]h&]uh1jvhj ubeh}(h]h ]h"]h$]h&]uh1jqhjlubjr)}(hhh]jw)}(hhh]h)}(h -- direct ioh]h -- direct io}(hjS!hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMWhjP!ubah}(h]h ]h"]h$]h&]morecolsKuh1jvhjM!ubah}(h]h ]h"]h$]h&]uh1jqhjlubjr)}(hhh](jw)}(hhh]h)}(hWRITE_LIFE_EXTREMEh]hWRITE_LIFE_EXTREME}(hjt!hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMYhjq!ubah}(h]h ]h"]h$]h&]uh1jvhjn!ubjw)}(hhh]h)}(h COLD_DATAh]h COLD_DATA}(hj!hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMYhj!ubah}(h]h ]h"]h$]h&]uh1jvhjn!ubjw)}(hhh]h)}(hWRITE_LIFE_EXTREMEh]hWRITE_LIFE_EXTREME}(hj!hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMYhj!ubah}(h]h ]h"]h$]h&]uh1jvhjn!ubeh}(h]h ]h"]h$]h&]uh1jqhjlubjr)}(hhh](jw)}(hhh]h)}(hWRITE_LIFE_SHORTh]hWRITE_LIFE_SHORT}(hj!hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMZhj!ubah}(h]h ]h"]h$]h&]uh1jvhj!ubjw)}(hhh]h)}(hHOT_DATAh]hHOT_DATA}(hj!hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMZhj!ubah}(h]h ]h"]h$]h&]uh1jvhj!ubjw)}(hhh]h)}(hWRITE_LIFE_SHORTh]hWRITE_LIFE_SHORT}(hj!hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMZhj!ubah}(h]h ]h"]h$]h&]uh1jvhj!ubeh}(h]h ]h"]h$]h&]uh1jqhjlubjr)}(hhh](jw)}(hhh]h)}(hWRITE_LIFE_NOT_SETh]hWRITE_LIFE_NOT_SET}(hj"hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM[hj "ubah}(h]h ]h"]h$]h&]uh1jvhj "ubjw)}(hhh]h)}(h WARM_DATAh]h WARM_DATA}(hj'"hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM[hj$"ubah}(h]h ]h"]h$]h&]uh1jvhj "ubjw)}(hhh]h)}(hWRITE_LIFE_NOT_SETh]hWRITE_LIFE_NOT_SET}(hj>"hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM[hj;"ubah}(h]h ]h"]h$]h&]uh1jvhj "ubeh}(h]h ]h"]h$]h&]uh1jqhjlubjr)}(hhh](jw)}(hhh]h)}(hWRITE_LIFE_NONEh]hWRITE_LIFE_NONE}(hj^"hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM\hj["ubah}(h]h ]h"]h$]h&]uh1jvhjX"ubjw)}(hhh]h)}(hj h]h“}(hju"hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM\hjr"ubah}(h]h ]h"]h$]h&]uh1jvhjX"ubjw)}(hhh]h)}(hWRITE_LIFE_NONEh]hWRITE_LIFE_NONE}(hj"hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM\hj"ubah}(h]h ]h"]h$]h&]uh1jvhjX"ubeh}(h]h ]h"]h$]h&]uh1jqhjlubjr)}(hhh](jw)}(hhh]h)}(hWRITE_LIFE_MEDIUMh]hWRITE_LIFE_MEDIUM}(hj"hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM]hj"ubah}(h]h ]h"]h$]h&]uh1jvhj"ubjw)}(hhh]h)}(hj h]h“}(hj"hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM]hj"ubah}(h]h ]h"]h$]h&]uh1jvhj"ubjw)}(hhh]h)}(hWRITE_LIFE_MEDIUMh]hWRITE_LIFE_MEDIUM}(hj"hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM]hj"ubah}(h]h ]h"]h$]h&]uh1jvhj"ubeh}(h]h ]h"]h$]h&]uh1jqhjlubjr)}(hhh](jw)}(hhh]h)}(hWRITE_LIFE_LONGh]hWRITE_LIFE_LONG}(hj"hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM^hj"ubah}(h]h ]h"]h$]h&]uh1jvhj"ubjw)}(hhh]h)}(hj h]h“}(hj#hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM^hj #ubah}(h]h ]h"]h$]h&]uh1jvhj"ubjw)}(hhh]h)}(hWRITE_LIFE_LONGh]hWRITE_LIFE_LONG}(hj%#hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM^hj"#ubah}(h]h ]h"]h$]h&]uh1jvhj"ubeh}(h]h ]h"]h$]h&]uh1jqhjlubeh}(h]h ]h"]h$]h&]uh1jlhjubeh}(h]h ]h"]h$]h&]colsKuh1jQhjubah}(h]h ]h"]h$]h&]uh1jLhjhhhhhNubeh}(h]write-hint-policyah ]h"]write-hint policyah$]h&]uh1hhjhhhhhMCubh)}(hhh](h)}(hFallocate(2) Policyh]hFallocate(2) Policy}(hj]#hhhNhNubah}(h]h ]h"]h$]h&]uh1hhjZ#hhhhhMbubh)}(h0The default policy follows the below POSIX rule.h]h0The default policy follows the below POSIX rule.}(hjk#hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMdhjZ#hhubjA)}(hhh]jF)}(hX&Allocating disk space The default operation (i.e., mode is zero) of fallocate() allocates the disk space within the range specified by offset and len. The file size (as reported by stat(2)) will be changed if offset+len is greater than the file size. Any subregion within the range specified by offset and len that did not contain data before the call will be initialized to zero. This default behavior closely resembles the behavior of the posix_fallocate(3) library function, and is intended as a method of optimally implementing that function. h](jL)}(hAllocating disk spaceh]hAllocating disk space}(hj#hhhNhNubah}(h]h ]h"]h$]h&]uh1jKhhhMnhj|#ubj\)}(hhh]h)}(hXThe default operation (i.e., mode is zero) of fallocate() allocates the disk space within the range specified by offset and len. The file size (as reported by stat(2)) will be changed if offset+len is greater than the file size. Any subregion within the range specified by offset and len that did not contain data before the call will be initialized to zero. This default behavior closely resembles the behavior of the posix_fallocate(3) library function, and is intended as a method of optimally implementing that function.h]hXThe default operation (i.e., mode is zero) of fallocate() allocates the disk space within the range specified by offset and len. The file size (as reported by stat(2)) will be changed if offset+len is greater than the file size. Any subregion within the range specified by offset and len that did not contain data before the call will be initialized to zero. This default behavior closely resembles the behavior of the posix_fallocate(3) library function, and is intended as a method of optimally implementing that function.}(hj#hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMghj#ubah}(h]h ]h"]h$]h&]uh1j[hj|#ubeh}(h]h ]h"]h$]h&]uh1jEhhhMnhjy#ubah}(h]h ]h"]h$]h&]uh1j@hjZ#hhhhhNubh)}(hHowever, once F2FS receives ioctl(fd, F2FS_IOC_SET_PIN_FILE) in prior to fallocate(fd, DEFAULT_MODE), it allocates on-disk block addresses having zero or random data, which is useful to the below scenario where:h]hHowever, once F2FS receives ioctl(fd, F2FS_IOC_SET_PIN_FILE) in prior to fallocate(fd, DEFAULT_MODE), it allocates on-disk block addresses having zero or random data, which is useful to the below scenario where:}(hj#hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMphjZ#hhubj)}(h1. create(fd) 2. ioctl(fd, F2FS_IOC_SET_PIN_FILE) 3. fallocate(fd, 0, 0, size) 4. address = fibmap(fd, offset) 5. open(blkdev) 6. write(blkdev, address) h]jw)}(hhh](j.)}(h create(fd)h]h)}(hj#h]h create(fd)}(hj#hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMthj#ubah}(h]h ]h"]h$]h&]uh1j-hj#ubj.)}(h ioctl(fd, F2FS_IOC_SET_PIN_FILE)h]h)}(hj#h]h ioctl(fd, F2FS_IOC_SET_PIN_FILE)}(hj#hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMuhj#ubah}(h]h ]h"]h$]h&]uh1j-hj#ubj.)}(hfallocate(fd, 0, 0, size)h]h)}(hj#h]hfallocate(fd, 0, 0, size)}(hj#hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMvhj#ubah}(h]h ]h"]h$]h&]uh1j-hj#ubj.)}(haddress = fibmap(fd, offset)h]h)}(hj $h]haddress = fibmap(fd, offset)}(hj$hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMwhj $ubah}(h]h ]h"]h$]h&]uh1j-hj#ubj.)}(h open(blkdev)h]h)}(hj$$h]h open(blkdev)}(hj&$hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMxhj"$ubah}(h]h ]h"]h$]h&]uh1j-hj#ubj.)}(hwrite(blkdev, address) h]h)}(hwrite(blkdev, address)h]hwrite(blkdev, address)}(hj=$hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMyhj9$ubah}(h]h ]h"]h$]h&]uh1j-hj#ubeh}(h]h ]h"]h$]h&]jjjhjjuh1jvhj#ubah}(h]h ]h"]h$]h&]uh1jhhhMthjZ#hhubeh}(h]fallocate-2-policyah ]h"]fallocate(2) policyah$]h&]uh1hhjhhhhhMbubh)}(hhh](h)}(hCompression implementationh]hCompression implementation}(hjh$hhhNhNubah}(h]h ]h"]h$]h&]uh1hhje$hhhhhM|ubj))}(hhh](j.)}(hNew term named cluster is defined as basic unit of compression, file can be divided into multiple clusters logically. One cluster includes 4 << n (n >= 0) logical pages, compression size is also cluster size, each of cluster can be compressed or not. h]h)}(hNew term named cluster is defined as basic unit of compression, file can be divided into multiple clusters logically. One cluster includes 4 << n (n >= 0) logical pages, compression size is also cluster size, each of cluster can be compressed or not.h]hNew term named cluster is defined as basic unit of compression, file can be divided into multiple clusters logically. One cluster includes 4 << n (n >= 0) logical pages, compression size is also cluster size, each of cluster can be compressed or not.}(hj}$hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhM~hjy$ubah}(h]h ]h"]h$]h&]uh1j-hjv$hhhhhNubj.)}(hXIn cluster metadata layout, one special block address is used to indicate a cluster is a compressed one or normal one; for compressed cluster, following metadata maps cluster to [1, 4 << n - 1] physical blocks, in where f2fs stores data including compress header and compressed data. h]h)}(hXIn cluster metadata layout, one special block address is used to indicate a cluster is a compressed one or normal one; for compressed cluster, following metadata maps cluster to [1, 4 << n - 1] physical blocks, in where f2fs stores data including compress header and compressed data.h]hXIn cluster metadata layout, one special block address is used to indicate a cluster is a compressed one or normal one; for compressed cluster, following metadata maps cluster to [1, 4 << n - 1] physical blocks, in where f2fs stores data including compress header and compressed data.}(hj$hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj$ubah}(h]h ]h"]h$]h&]uh1j-hjv$hhhhhNubj.)}(hXIn order to eliminate write amplification during overwrite, F2FS only support compression on write-once file, data can be compressed only when all logical blocks in cluster contain valid data and compress ratio of cluster data is lower than specified threshold. h]h)}(hXIn order to eliminate write amplification during overwrite, F2FS only support compression on write-once file, data can be compressed only when all logical blocks in cluster contain valid data and compress ratio of cluster data is lower than specified threshold.h]hXIn order to eliminate write amplification during overwrite, F2FS only support compression on write-once file, data can be compressed only when all logical blocks in cluster contain valid data and compress ratio of cluster data is lower than specified threshold.}(hj$hhhNhNubah}(h]h ]h"]h$]h&]uh1hhhhMhj$ubah}(h]h ]h"]h$]h&]uh1j-hjv$hhhhhNubj.)}(hTo enable compression on regular inode, there are four ways: * chattr +c file * chattr +c dir; touch dir/file * mount w/ -o compress_extension=ext; touch file.ext * mount w/ -o compress_extension=*; touch any_file h](h)}(h /proc/sys/vm/drop_caches /* mmap(MAP_POPULATE) + mlock() */ # f2fs_io read 128 0 1024 mmap 1 0 /data/testfile_read_seq /* mmap() + fadvise(POSIX_FADV_WILLNEED) + mlock() */ # f2fs_io read 128 0 1024 fadvise 1 0 /data/testfile_read_seq /* mmap() + mlock2(MLOCK_ONFAULT) + madvise(MADV_POPULATE_READ) */ # f2fs_io read 128 0 1024 madvise 1 0 /data/testfile_read_seq # f2fs_io clearflags immutable /data/testfile_read_seq # f2fs_io write 1 0 1 zero buffered /data/testfile_read_seq Failed to open /mnt/test/test: Operation not supported /* flush and reload the inode to disable the large folio */ # sync && echo 3 > /proc/sys/vm/drop_caches # f2fs_io write 1 0 1 zero buffered /data/testfile_read_seq Written 4096 bytes with pattern = zero, total_time = 29 us, max_latency = 28 us # rm /data/testfile_read_seqh]hX# f2fs_io setflags immutable /data/testfile_read_seq /* flush and reload the inode to enable the large folio */ # sync && echo 3 > /proc/sys/vm/drop_caches /* mmap(MAP_POPULATE) + mlock() */ # f2fs_io read 128 0 1024 mmap 1 0 /data/testfile_read_seq /* mmap() + fadvise(POSIX_FADV_WILLNEED) + mlock() */ # f2fs_io read 128 0 1024 fadvise 1 0 /data/testfile_read_seq /* mmap() + mlock2(MLOCK_ONFAULT) + madvise(MADV_POPULATE_READ) */ # f2fs_io read 128 0 1024 madvise 1 0 /data/testfile_read_seq # f2fs_io clearflags immutable /data/testfile_read_seq # f2fs_io write 1 0 1 zero buffered /data/testfile_read_seq Failed to open /mnt/test/test: Operation not supported /* flush and reload the inode to disable the large folio */ # sync && echo 3 > /proc/sys/vm/drop_caches # f2fs_io write 1 0 1 zero buffered /data/testfile_read_seq Written 4096 bytes with pattern = zero, total_time = 29 us, max_latency = 28 us # rm /data/testfile_read_seq}hj(sbah}(h]h ]h"]h$]h&]hhj" j# jM'j% }uh1j hhhMMhj'hhubeh}(h]&per-file-read-only-large-folio-supportah ]h"]&per-file read-only large folio supportah$]h&]uh1hhjhhhhhM@ubeh}(h]designah ]h"]designah$]h&]uh1hhhhhhhhM6ubeh}(h]flash-friendly-file-system-f2fsah ]h"]!flash-friendly file system (f2fs)ah$]h&]uh1hhhhhhhhKubeh}(h]h ]h"]h$]h&]sourcehuh1hcurrent_sourceN current_lineNsettingsdocutils.frontendValues)}(hN generatorN datestampN source_linkN source_urlN toc_backlinksjvfootnote_backlinksK sectnum_xformKstrip_commentsNstrip_elements_with_classesN strip_classesN report_levelK halt_levelKexit_status_levelKdebugNwarning_streamN tracebackinput_encoding utf-8-siginput_encoding_error_handlerstrictoutput_encodingutf-8output_encoding_error_handlerjX(error_encodingutf-8error_encoding_error_handlerbackslashreplace language_codeenrecord_dependenciesNconfigN id_prefixhauto_id_prefixid dump_settingsNdump_internalsNdump_transformsNdump_pseudo_xmlNexpose_internalsNstrict_visitorN_disable_configN_sourcehnj _destinationN _config_files]7/var/lib/git/docbuild/linux/Documentation/docutils.confafile_insertion_enabled raw_enabledKline_length_limitM'pep_referencesN pep_base_urlhttps://peps.python.org/pep_file_url_templatepep-%04drfc_referencesN rfc_base_url&https://datatracker.ietf.org/doc/html/ tab_widthKtrim_footnote_reference_spacesyntax_highlightlong smart_quotessmartquotes_locales]character_level_inline_markupdoctitle_xform docinfo_xformKsectsubtitle_xform image_loadinglinkembed_stylesheetcloak_email_addressessection_self_linkenvNubreporterNindirect_targets]substitution_defs}substitution_names}refnames}refids}nameids}(j3(j0(jjjjjjwandering tree problemNcleaning overheadNj8j5jbj_j^j[jjj#j jjjBj?jjjj jCj@jxjujjjjj+(j((jjjIjFjjjjjjjjjW#jT#jb$j_$j &j&j&j&j'j 'jb'j_'j'j'j#(j (u nametypes}(j3(jjjj(j(j8jbj^jj#jjBjjjCjxjjj+(jjIjjjjjW#jb$j &j&j'jb'j'j#(uh}(j0(hjhjjjjjBjjjIj5jj_jjjej.jj[j;jjaj jjj&j?jjjEj jj@jjujFjj{jjj((jjjjFj jjLjjjjjjjT#jj_$jZ#j&je$j&j#&j 'j&j_'j'j'je'j (j'u footnote_refs} citation_refs} autofootnotes]autofootnote_refs]symbol_footnotes]symbol_footnote_refs] footnotes] citations]autofootnote_startKsymbol_footnote_startK id_counter collectionsCounter}jf(KsRparse_messages](hsystem_message)}(hhh]h)}(h9Duplicate implicit target name: "wandering tree problem".h]h=Duplicate implicit target name: “wandering tree problem”.}(hj(hhhNhNubah}(h]h ]h"]h$]h&]uh1hhj(ubah}(h]h ]h"]h$]h&]jalevelKtypeINFOsourcehnjlineK_uh1j(hjehhhhhK_ubj()}(hhh]h)}(h4Duplicate implicit target name: "cleaning overhead".h]h8Duplicate implicit target name: “cleaning overhead”.}(hj(hhhNhNubah}(h]h ]h"]h$]h&]uh1hhj(ubah}(h]h ]h"]h$]h&]j.alevelKtypej(sourcehnjlineKeuh1j(hjhhhhhKeubj()}(hhh]h)}(heUnexpected possible title overline or transition. 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