xfs_repair - repair an XFS filesystem
SYNOPSIS
xfs_repair [ -nLvV ] [ -o subopt[=value] ]
[-l logdev] [-r rtdev] xfs_special
xfs_repair -f [ -nLvV ] [ -o subopt[=value] ]
[-l logfile] [-r rtfile] file
DESCRIPTION
xfs_repair repairs corrupt or damaged XFS filesystems (see
xfs(5)). The filesystem is specified using the xfs_spe
cial argument which should be the device name of the disk
partition or volume containing the filesystem. If given
the name of a block device, xfs_repair will attempt to
find the raw device associated with the specified block
device and will use the raw device instead.
Regardless, the filesystem to be repaired must be
unmounted, otherwise, the resulting filesystem may be
inconsistent or corrupt.
The options to xfs_repair are:
-f Specifies that the special device is actually a
file (see the mkfs.xfs -d file option). This might
happen if an image copy of a filesystem has been
copied or written into an ordinary file. This
option implies that any external log or realtime
section is also in an ordinary file.
-L Force Log Zeroing. Forces xfs_repair to zero the
log even if it is dirty (contains metadata
changes). When using this option the filesystem
will likely appear to be corrupt, and can cause the
loss of user files and/or data.
-l Specifies the device special file where the
filesystem's external log resides. Only for those
filesystems which use an external log. See the
mkfs.xfs -l option, and refer to xfs(5) for a
detailed description of the XFS log.
-r Specifies the device special file where the
filesystem's realtime section resides. Only for
those filesystems which use a realtime section.
See the mkfs.xfs -r option, and refer to xfs(5) for
a detailed description of the XFS realtime section.
-n No modify mode. Specifies that xfs_repair should
not modify the filesystem but should only scan the
filesystem and indicate what repairs would have
been made.
filesystem if left to its own devices.
The assume_xfs suboption specifies that the
filesystem is an XFS filesystem. Normally, if
xfs_repair cannot find an XFS superblock, it checks
to see if the filesystem is an EFS filesystem
before it tries to regenerate the XFS superblock.
If the assume_xfs option is in effect, xfs_repair
will assume that the filesystem is an XFS filesys
tem and will ignore an EFS superblock if one is
found.
-v Verbose output.
Checks Performed
Inconsistencies corrected include the following:
1. Inode and inode blockmap (addressing) checks: bad
magic number in inode, bad magic numbers in inode
blockmap blocks, extents out of order, incorrect
number of records in inode blockmap blocks, blocks
claimed that are not in a legal data area of the
filesystem, blocks that are claimed by more than
one inode.
2. Inode allocation map checks: bad magic number in
inode map blocks, inode state as indicated by map
(free or in-use) inconsistent with state indicated
by the inode, inodes referenced by the filesystem
that do not appear in the inode allocation map,
inode allocation map referencing blocks that do not
appear to contain inodes.
3. Size checks: number of blocks claimed by inode
inconsistent with inode size, directory size not
block aligned, inode size not consistent with inode
format.
4. Directory checks: bad magic numbers in directory
blocks, incorrect number of entries in a directory
block, bad freespace information in a directory
leaf block, entry pointing to an unallocated (free)
or out of range inode, overlapping entries, missing
or incorrect dot and dotdot entries, entries out of
hashvalue order, incorrect internal directory
pointers, directory type not consistent with inode
format and size.
5. Pathname checks: files or directories not refer
enced by a pathname starting from the filesystem
root, illegal pathname components.
6. Link count checks: link counts that do not agree
inode.
7. Freemap checks: blocks claimed free by the freemap
but also claimed by an inode, blocks unclaimed by
any inode but not appearing in the freemap.
8. Super Block checks: total free block and/or free i-
node count incorrect, filesystem geometry inconsis
tent, secondary and primary superblocks contradic
tory.
Orphaned files and directories (allocated, in-use but
unreferenced) are reconnected by placing them in the
lost+found directory. The name assigned is the inode num
ber.
Disk Errors
xfs_repair aborts on most disk I/O errors. Therefore, if
you are trying to repair a filesystem that was damaged due
to a disk drive failure, steps should be taken to ensure
that all blocks in the filesystem are readable and write
able before attempting to use xfs_repair to repair the
filesystem. A possible method is using dd(8) to copy the
data onto a good disk.
lost+found
The directory lost+found does not have to already exist in
the filesystem being repaired. If the directory does not
exist, it is automatically created. If the lost+found
directory already exists, the lost+found directory is
deleted and recreated every time xfs_repair runs. This
ensures that there are no name conflicts in lost+found.
However, if you rename a file in lost+found and leave it
there, if xfs_repair is run again, that file is renamed
back to its inode number.
Corrupted Superblocks
XFS has both primary and secondary superblocks.
xfs_repair uses information in the primary superblock to
automatically find and validate the primary superblock
against the secondary superblocks before proceeding.
Should the primary be too corrupted to be useful in locat
ing the secondary superblocks, the program scans the
filesystem until it finds and validates some secondary
superblocks. At that point, it generates a primary
superblock.
Quotas
If quotas are in use, it is possible that xfs_repair will
clear some or all of the filesystem quota information. If
so, the program issues a warning just before it termi
nates. If all quota information is lost, quotas are dis
abled and the program issues a warning to that effect.
limits. It is recommended that you check the quota limit
information manually after xfs_repair. Also, space usage
information is automatically regenerated the next time the
filesystem is mounted with quotas turned on, so the next
quota mount of the filesystem may take some time.
DIAGNOSTICS
xfs_repair issues informative messages as it proceeds
indicating what it has found that is abnormal or any cor
rective action that it has taken. Most of the messages
are completely understandable only to those who are knowl
edgeable about the structure of the filesystem. Some of
the more common messages are explained here. Note that
the language of the messages is slightly different if
xfs_repair is run in no-modify mode because the program is
not changing anything on disk. No-modify mode indicates
what it would do to repair the filesystem if run without
the no-modify flag.
disconnected inode xxxx, moving to lost+found
An inode numbered xxxx was not connected to the
filesystem directory tree and was reconnected to
the lost+found directory. The inode is assigned
the name of its inode number (i-number). If a
lost+found directory does not exist, it is automat
ically created.
disconnected dir inode xxxx, moving to lost+found
As above only the inode is a directory inode. If a
directory inode is attached to lost+found, all of
its children (if any) stay attached to the direc
tory and therefore get automatically reconnected
when the directory is reconnected.
imap claims in-use inode xxxx is free, correcting imap
The inode allocation map thinks that inode xxxx is
free whereas examination of the inode indicates
that the inode may be in use (although it may be
disconnected). The program updates the inode allo
cation map.
imap claims free inode xxxx is in use, correcting imap
The inode allocation map thinks that inode xxxx is
in use whereas examination of the inode indicates
that the inode is not in use and therefore is free.
The program updates the inode allocation map.
resetting inode xxxx nlinks from x to y
of valid directory entries referencing inode xxxx
and the number of references recorded in the inode
and corrected the the number in the inode.
fork-type fork in ino xxxx claims used block yyyy
Inode xxxx claims a block yyyy that is used
(claimed) by either another inode or the filesystem
itself for metadata storage. The fork-type is
either data or attr indicating whether the problem
lies in the portion of the inode that tracks regu
lar data or the portion of the inode that stores
XFS attributes. If the inode is a real-time (rt)
inode, the message says so. Any inode that claims
blocks used by the filesystem is deleted. If two
or more inodes claim the same block, they are both
deleted.
fork-type fork in ino xxxx claims dup extent ...
Inode xxxx claims a block in an extent known to be
claimed more than once. The offset in the inode,
start and length of the extent is given. The mes
sage is slightly different if the inode is a real-
time (rt) inode and the extent is therefore a real-
time (rt) extent.
inode xxxx - bad extent ...
An extent record in the blockmap of inode xxxx
claims blocks that are out of the legal range of
the filesystem. The message supplies the start,
end, and file offset of the extent. The message is
slightly different if the extent is a real-time
(rt) exent.
bad fork-type fork in inode xxxx
There was something structurally wrong or inconsis
tent with the data structures that map offsets to
filesystem blocks.
cleared inode xxxx
There was something wrong with the inode that was
uncorrectable so the program freed the inode. This
usually happens because the inode claims blocks
that are used by something else or the inode itself
is badly corrupted. Typically, this message is
preceded by one or more messages indicating why the
inode needed to be cleared.
bad attribute fork in inode xxxx, clearing attr fork
inode that stores XFS attributes (the attribute
fork) so the program reset the attribute fork. As
a result of this, all attributes on that inode are
lost.
correcting nextents for inode xxxx, was x - counted y
The program found that the number of extents used
to store the data in the inode is wrong and cor
rected the number. The message refers to nextents
if the count is wrong on the number of extents used
to store attribute information.
entry "name" in dir xxxx not consistent with .. value
(yyyy) in dir ino xxxx, junking entry "name" in directory
inode xxxx
The entry "name" in directory inode xxxx references
a directory inode yyyy. However, the .. entry in
directory yyyy does not point back to directory
xxxx, so the program deletes the entry "name" in
directory inode xxxx. If the directory inode yyyy
winds up becoming a disconnected inode as a result
of this, it is moved to lost+found later.
entry "name" in dir xxxx references already connected dir
ino yyyy, junking entry "name" in directory inode xxxx
The entry "name" in directory inode xxxx points to
a directory inode yyyy that is known to be a child
of another directory. Therefore, the entry is
invalid and is deleted. This message refers to an
entry in a small directory. If this were a large
directory, the last phrase would read "will clear
entry".
entry references free inode xxxx in directory yyyy, will
clear entry
An entry in directory inode yyyy references an
inode xxxx that is known to be free. The entry is
therefore invalid and is deleted. This message
refers to a large directory. If the directory were
small, the message would read "junking entry ...".
EXIT STATUS
xfs_repair -n (no modify node) will return a status of 1
if filesystem corruption was detected and 0 if no filesys
tem corruption was detected. xfs_repair run without the
-n option will always return a status code of 0.
BUGS
The filesystem to be checked and repaired must have been
cedures (the umount(8) command or system shutdown), not as
a result of a crash or system reset. If the filesystem
has not been unmounted cleanly, mount it and unmount it
cleanly before running xfs_repair.
xfs_repair does not do a thorough job on XFS extended
attributes. The structure of the attribute fork will be
consistent, but only the contents of attribute forks that
will fit into an inode are checked. This limitation will
be fixed in the future.
The no-modify mode (-n option) is not completely accurate.
It does not catch inconsistencies in the freespace and
inode maps, particularly lost blocks or subtly corrupted
maps (trees).
The no-modify mode can generate repeated warnings about
the same problems because it cannot fix the problems as
they are encountered.
SEE ALSO
dd(1), mkfs.xfs(8), umount(8), xfs_check(8), xfs(5).
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