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author | Lukas Czerner <lczerner@redhat.com> | 2020-03-03 14:53:48 +0100 |
---|---|---|
committer | Theodore Ts'o <tytso@mit.edu> | 2020-03-07 12:50:02 -0500 |
commit | ca84539d5fa32061fa1ea09296990b30866f1f84 (patch) | |
tree | 81bee253ed5ee337439c0bbdc1406f53df1a0551 | |
parent | f106b01c98d7abc12af39aad4024f17ffa14dc06 (diff) | |
download | e2fsprogs-ca84539d5fa32061fa1ea09296990b30866f1f84.tar.gz |
libext2fs: check open(O_EXCL) first in ismounted.c
Currently the ext2fs_check_mount_point() will use the open(O_EXCL) check
on linux after all the other checks are done. However it is not
necessary to check mntent if open(O_EXCL) succeeds because it means that
the device is not mounted.
Moreover the commit ea4d53b7 introduced a regression where a following
set of commands fails:
vgcreate mygroup /dev/sda
lvcreate -L 1G -n lvol0 mygroup
mkfs.ext4 /dev/mygroup/lvol0
mount /dev/mygroup/lvol0 /mnt
lvrename /dev/mygroup/lvol0 /dev/mygroup/lvol1
lvcreate -L 1G -n lvol0 mygroup
mkfs.ext4 /dev/mygroup/lvol0 <<<--- This fails
It fails because it thinks that /dev/mygroup/lvol0 is mounted because
the device name in /proc/mounts is not updated following the lvrename.
Move the open(O_EXCL) check before the mntent check and return
immediatelly if the device is not busy.
Fixes: ea4d53b7 ("libext2fs/ismounted.c: check device id in advance to skip false device names")
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Reported-by: Zdenek Kabelac <zkabelac@redhat.com>
Reported-by: Karel Zak <kzak@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
-rw-r--r-- | lib/ext2fs/ismounted.c | 42 |
1 files changed, 27 insertions, 15 deletions
diff --git a/lib/ext2fs/ismounted.c b/lib/ext2fs/ismounted.c index c02156925..46d330d98 100644 --- a/lib/ext2fs/ismounted.c +++ b/lib/ext2fs/ismounted.c @@ -352,6 +352,7 @@ errcode_t ext2fs_check_mount_point(const char *device, int *mount_flags, char *mtpt, int mtlen) { errcode_t retval = 0; + int busy = 0; if (getenv("EXT2FS_PRETEND_RO_MOUNT")) { *mount_flags = EXT2_MF_MOUNTED | EXT2_MF_READONLY; @@ -366,6 +367,30 @@ errcode_t ext2fs_check_mount_point(const char *device, int *mount_flags, return 0; } +#ifdef __linux__ /* This only works on Linux 2.6+ systems */ + { + struct stat st_buf; + + if (stat(device, &st_buf) == 0 && + ext2fsP_is_disk_device(st_buf.st_mode)) { + int fd = open(device, O_RDONLY | O_EXCL); + + if (fd >= 0) { + /* + * The device is not busy so it's + * definitelly not mounted. No need to + * to perform any more checks. + */ + close(fd); + *mount_flags = 0; + return 0; + } else if (errno == EBUSY) { + busy = 1; + } + } + } +#endif + if (is_swap_device(device)) { *mount_flags = EXT2_MF_MOUNTED | EXT2_MF_SWAP; strncpy(mtpt, "<swap>", mtlen); @@ -386,21 +411,8 @@ errcode_t ext2fs_check_mount_point(const char *device, int *mount_flags, if (retval) return retval; -#ifdef __linux__ /* This only works on Linux 2.6+ systems */ - { - struct stat st_buf; - - if (stat(device, &st_buf) == 0 && - ext2fsP_is_disk_device(st_buf.st_mode)) { - int fd = open(device, O_RDONLY | O_EXCL); - - if (fd >= 0) - close(fd); - else if (errno == EBUSY) - *mount_flags |= EXT2_MF_BUSY; - } - } -#endif + if (busy) + *mount_flags |= EXT2_MF_BUSY; return 0; } |