€•–%Œsphinx.addnodes”Œdocument”“”)”}”(Œ rawsource”Œ”Œchildren”]”(Œ translations”Œ LanguagesNode”“”)”}”(hhh]”(hŒ pending_xref”“”)”}”(hhh]”Œdocutils.nodes”ŒText”“”ŒChinese (Simplified)”…””}”Œparent”hsbaŒ attributes”}”(Œids”]”Œclasses”]”Œnames”]”Œdupnames”]”Œbackrefs”]”Œ refdomain”Œstd”Œreftype”Œdoc”Œ reftarget”Œ*/translations/zh_CN/filesystems/ext4/about”Œmodname”NŒ classname”NŒ refexplicit”ˆuŒtagname”hhh ubh)”}”(hhh]”hŒChinese (Traditional)”…””}”hh2sbah}”(h]”h ]”h"]”h$]”h&]”Œ refdomain”h)Œreftype”h+Œ reftarget”Œ*/translations/zh_TW/filesystems/ext4/about”Œmodname”NŒ classname”NŒ refexplicit”ˆuh1hhh ubh)”}”(hhh]”hŒItalian”…””}”hhFsbah}”(h]”h ]”h"]”h$]”h&]”Œ refdomain”h)Œreftype”h+Œ reftarget”Œ*/translations/it_IT/filesystems/ext4/about”Œmodname”NŒ classname”NŒ refexplicit”ˆuh1hhh ubh)”}”(hhh]”hŒJapanese”…””}”hhZsbah}”(h]”h ]”h"]”h$]”h&]”Œ refdomain”h)Œreftype”h+Œ reftarget”Œ*/translations/ja_JP/filesystems/ext4/about”Œmodname”NŒ classname”NŒ refexplicit”ˆuh1hhh ubh)”}”(hhh]”hŒKorean”…””}”hhnsbah}”(h]”h ]”h"]”h$]”h&]”Œ refdomain”h)Œreftype”h+Œ reftarget”Œ*/translations/ko_KR/filesystems/ext4/about”Œmodname”NŒ classname”NŒ refexplicit”ˆuh1hhh ubh)”}”(hhh]”hŒSpanish”…””}”hh‚sbah}”(h]”h ]”h"]”h$]”h&]”Œ refdomain”h)Œreftype”h+Œ reftarget”Œ*/translations/sp_SP/filesystems/ext4/about”Œmodname”NŒ classname”NŒ refexplicit”ˆuh1hhh ubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h hhŒ _document”hŒsource”NŒline”NubhŒcomment”“”)”}”(hŒ SPDX-License-Identifier: GPL-2.0”h]”hŒ SPDX-License-Identifier: GPL-2.0”…””}”hh£sbah}”(h]”h ]”h"]”h$]”h&]”Œ xml:space”Œpreserve”uh1h¡hhhžhhŸŒD/var/lib/git/docbuild/linux/Documentation/filesystems/ext4/about.rst”h KubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒAbout this Book”h]”hŒAbout this Book”…””}”(hh»hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hh¶hžhhŸh³h KubhŒ paragraph”“”)”}”(hŒîThis document attempts to describe the on-disk format for ext4 filesystems. The same general ideas should apply to ext2/3 filesystems as well, though they do not support all the features that ext4 supports, and the fields will be shorter.”h]”hŒîThis document attempts to describe the on-disk format for ext4 filesystems. The same general ideas should apply to ext2/3 filesystems as well, though they do not support all the features that ext4 supports, and the fields will be shorter.”…””}”(hhËhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Khh¶hžhubhÊ)”}”(hXp**NOTE**: This is a work in progress, based on notes that the author (djwong) made while picking apart a filesystem by hand. The data structure definitions should be current as of Linux 4.18 and e2fsprogs-1.44. All comments and corrections are welcome, since there is undoubtedly plenty of lore that might not be reflected in freshly created demonstration filesystems.”h]”(hŒstrong”“”)”}”(hŒ**NOTE**”h]”hŒNOTE”…””}”(hhßhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÝhhÙubhXh: This is a work in progress, based on notes that the author (djwong) made while picking apart a filesystem by hand. The data structure definitions should be current as of Linux 4.18 and e2fsprogs-1.44. All comments and corrections are welcome, since there is undoubtedly plenty of lore that might not be reflected in freshly created demonstration filesystems.”…””}”(hhÙhžhhŸNh Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K hh¶hžhubhµ)”}”(hhh]”(hº)”}”(hŒLicense”h]”hŒLicense”…””}”(hhúhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hh÷hžhhŸh³h KubhÊ)”}”(hŒDThis book is licensed under the terms of the GNU Public License, v2.”h]”hŒDThis book is licensed under the terms of the GNU Public License, v2.”…””}”(hjhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Khh÷hžhubeh}”(h]”Œlicense”ah ]”h"]”Œlicense”ah$]”h&]”uh1h´hh¶hžhhŸh³h Kubhµ)”}”(hhh]”(hº)”}”(hŒ Terminology”h]”hŒ Terminology”…””}”(hj!hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hjhžhhŸh³h KubhÊ)”}”(hX^ext4 divides a storage device into an array of logical blocks both to reduce bookkeeping overhead and to increase throughput by forcing larger transfer sizes. Generally, the block size will be 4KiB (the same size as pages on x86 and the block layer's default block size), though the actual size is calculated as 2 ^ (10 + ``sb.s_log_block_size``) bytes. Throughout this document, disk locations are given in terms of these logical blocks, not raw LBAs, and not 1024-byte blocks. For the sake of convenience, the logical block size will be referred to as ``$block_size`` throughout the rest of the document.”h]”(hXDext4 divides a storage device into an array of logical blocks both to reduce bookkeeping overhead and to increase throughput by forcing larger transfer sizes. Generally, the block size will be 4KiB (the same size as pages on x86 and the block layer’s default block size), though the actual size is calculated as 2 ^ (10 + ”…””}”(hj/hžhhŸNh NubhŒliteral”“”)”}”(hŒ``sb.s_log_block_size``”h]”hŒsb.s_log_block_size”…””}”(hj9hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j7hj/ubhŒÑ) bytes. Throughout this document, disk locations are given in terms of these logical blocks, not raw LBAs, and not 1024-byte blocks. For the sake of convenience, the logical block size will be referred to as ”…””}”(hj/hžhhŸNh Nubj8)”}”(hŒ``$block_size``”h]”hŒ $block_size”…””}”(hjKhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j7hj/ubhŒ% throughout the rest of the document.”…””}”(hj/hžhhŸNh Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KhjhžhubhÊ)”}”(hŒ”When referenced in ``preformatted text`` blocks, ``sb`` refers to fields in the super block, and ``inode`` refers to fields in an inode table entry.”h]”(hŒWhen referenced in ”…””}”(hjchžhhŸNh Nubj8)”}”(hŒ``preformatted text``”h]”hŒpreformatted text”…””}”(hjkhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j7hjcubhŒ blocks, ”…””}”(hjchžhhŸNh Nubj8)”}”(hŒ``sb``”h]”hŒsb”…””}”(hj}hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j7hjcubhŒ* refers to fields in the super block, and ”…””}”(hjchžhhŸNh Nubj8)”}”(hŒ ``inode``”h]”hŒinode”…””}”(hjhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1j7hjcubhŒ* refers to fields in an inode table entry.”…””}”(hjchžhhŸNh Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K#hjhžhubeh}”(h]”Œ terminology”ah ]”h"]”Œ terminology”ah$]”h&]”uh1h´hh¶hžhhŸh³h Kubhµ)”}”(hhh]”(hº)”}”(hŒOther References”h]”hŒOther References”…””}”(hj²hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hj¯hžhhŸh³h K(ubhÊ)”}”(hŒ–Also see https://www.nongnu.org/ext2-doc/ for quite a collection of information about ext2/3. Here's another old reference: http://wiki.osdev.org/Ext2”h]”(hŒ Also see ”…””}”(hjÀhžhhŸNh NubhŒ reference”“”)”}”(hŒ https://www.nongnu.org/ext2-doc/”h]”hŒ https://www.nongnu.org/ext2-doc/”…””}”(hjÊhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”Œrefuri”jÌuh1jÈhjÀubhŒU for quite a collection of information about ext2/3. Here’s another old reference: ”…””}”(hjÀhžhhŸNh NubjÉ)”}”(hŒhttp://wiki.osdev.org/Ext2”h]”hŒhttp://wiki.osdev.org/Ext2”…””}”(hjÝhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”Œrefuri”jßuh1jÈhjÀubeh}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K*hj¯hžhubeh}”(h]”Œother-references”ah ]”h"]”Œother references”ah$]”h&]”uh1h´hh¶hžhhŸh³h K(ubeh}”(h]”Œabout-this-book”ah ]”h"]”Œabout this book”ah$]”h&]”uh1h´hhhžhhŸh³h Kubeh}”(h]”h ]”h"]”h$]”h&]”Œsource”h³uh1hŒcurrent_source”NŒ current_line”NŒsettings”Œdocutils.frontend”ŒValues”“”)”}”(h¹NŒ generator”NŒ datestamp”NŒ source_link”NŒ source_url”NŒ toc_backlinks”Œentry”Œfootnote_backlinks”KŒ sectnum_xform”KŒstrip_comments”NŒstrip_elements_with_classes”NŒ strip_classes”NŒ report_level”KŒ halt_level”KŒexit_status_level”KŒdebug”NŒwarning_stream”NŒ traceback”ˆŒinput_encoding”Œ utf-8-sig”Œinput_encoding_error_handler”Œstrict”Œoutput_encoding”Œutf-8”Œoutput_encoding_error_handler”j%Œerror_encoding”Œutf-8”Œerror_encoding_error_handler”Œbackslashreplace”Œ language_code”Œen”Œrecord_dependencies”NŒconfig”NŒ id_prefix”hŒauto_id_prefix”Œid”Œ dump_settings”NŒdump_internals”NŒdump_transforms”NŒdump_pseudo_xml”NŒexpose_internals”NŒstrict_visitor”NŒ_disable_config”NŒ_source”h³Œ _destination”NŒ _config_files”]”Œ7/var/lib/git/docbuild/linux/Documentation/docutils.conf”aŒfile_insertion_enabled”ˆŒ raw_enabled”KŒline_length_limit”M'Œpep_references”NŒ pep_base_url”Œhttps://peps.python.org/”Œpep_file_url_template”Œpep-%04d”Œrfc_references”NŒ rfc_base_url”Œ&https://datatracker.ietf.org/doc/html/”Œ tab_width”KŒtrim_footnote_reference_space”‰Œsyntax_highlight”Œlong”Œ smart_quotes”ˆŒsmartquotes_locales”]”Œcharacter_level_inline_markup”‰Œdoctitle_xform”‰Œ docinfo_xform”KŒsectsubtitle_xform”‰Œ image_loading”Œlink”Œembed_stylesheet”‰Œcloak_email_addresses”ˆŒsection_self_link”‰Œenv”NubŒreporter”NŒindirect_targets”]”Œsubstitution_defs”}”Œsubstitution_names”}”Œrefnames”}”Œrefids”}”Œnameids”}”(jÿjüjjj¬j©j÷jôuŒ nametypes”}”(jÿ‰j‰j¬‰j÷‰uh}”(jüh¶jh÷j©jjôj¯uŒ footnote_refs”}”Œ citation_refs”}”Œ autofootnotes”]”Œautofootnote_refs”]”Œsymbol_footnotes”]”Œsymbol_footnote_refs”]”Œ footnotes”]”Œ citations”]”Œautofootnote_start”KŒsymbol_footnote_start”KŒ id_counter”Œ collections”ŒCounter”“”}”…”R”Œparse_messages”]”Œtransform_messages”]”Œ transformer”NŒ include_log”]”Œ decoration”Nhžhub.