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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | CONCEPTS | FILE I/O COMMANDS | MEMORY MAPPED I/O COMMANDS | FILESYSTEM COMMANDS | OTHER COMMANDS | SEE ALSO | COLOPHON |
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xfs_io(8) System Manager's Manual xfs_io(8)
xfs_io - debug the I/O path of an XFS filesystem
xfs_io [ -adfimrRstxT ] [ -c cmd ] ... [ -C cmd ] ... [ -p prog ]
[ file ]
xfs_io -V
xfs_io is a debugging tool like xfs_db(8), but is aimed at
examining the regular file I/O paths rather than the raw XFS
volume itself. These code paths include not only the obvious
read/write/mmap interfaces for manipulating files, but also cover
all of the XFS extensions (such as space preallocation, additional
inode flags, etc).
xfs_io commands may be run interactively (the default) or as
arguments on the command line. Interactive mode always runs
commands on the current open file, whilst commands run from the
command line may be repeated on all open files rather than just
the current open file. In general, open file iteration will occur
for commands that operate on file content or state. In contrast,
commands that operate on filesystem or system-wide state will only
be run on the current file regardless of how many files are
currently open. Multiple arguments may be given on the command
line and they are run in the sequence given. The program exits one
all commands have been run.
-c cmd Run the specified command on all currently open files. To
maintain compatibility with historical usage, commands that
can not be run on all open files will still be run but only
execute once on the current open file. Multiple -c
arguments may be given and may be interleaved on the
command line in any order with -C commands.
-C cmd Run the specified command only on the current open file.
Multiple -C arguments may be given and may be interleaved
on the command line in any order with -c commands.
-p prog
Set the program name for prompts and some error messages,
the default value is xfs_io.
-f Create file if it does not already exist.
-r Open file read-only, initially. This is required if file is
immutable or append-only.
-i Start an idle thread. The purpose of this idle thread is to
test io from a multi threaded process. With single threaded
process, the file table is not shared and file structs are
not reference counted. Spawning an idle thread can help
detecting file struct reference leaks.
-x Expert mode. Dangerous commands are only available in this
mode. These commands also tend to require additional
privileges.
-V Prints the version number and exits.
The other open(2) options described below are also available from
the command line.
xfs_io maintains a number of open files and memory mappings.
Files can be initially opened on the command line (optionally),
and additional files can also be opened later.
xfs_io commands can be broken up into three groups. Some commands
are aimed at doing regular file I/O - read, write, sync, space
preallocation, etc.
The second set of commands exist for manipulating memory mapped
regions of a file - mapping, accessing, storing, unmapping,
flushing, etc.
The remaining commands are for the navigation and display of data
structures relating to the open files, mappings, and the
filesystems where they reside.
Many commands have extensive online help. Use the help command for
more details on any command.
file [ N ]
Display a list of all open files and (optionally) switch to
an alternate current open file.
open [[ -acdfrstRTPL ] path ]
Closes the current file, and opens the file specified by
path instead. Without any arguments, displays statistics
about the current file - see the stat command.
-a opens append-only (O_APPEND).
-d opens for direct I/O (O_DIRECT).
-f creates the file if it doesn't already exist
(O_CREAT).
-r opens read-only (O_RDONLY).
-s opens for synchronous I/O (O_SYNC).
-t truncates on open (O_TRUNC).
-n opens in non-blocking mode if possible (O_NONBLOCK).
-T create a temporary file not linked into the
filesystem namespace (O_TMPFILE). The pathname
passed must refer to a directory which is treated as
virtual parent for the newly created invisible file.
Can not be used together with the -r option.
-R marks the file as a realtime XFS file after opening
it, if it is not already marked as such.
-P opens the path as a referent only (O_PATH). This is
incompatible with other flags specifying other O_xxx
flags apart from -L.
-L doesn't follow symlinks (O_NOFOLLOW). This is
incompatible with other flags specifying other O_xxx
flags apart from -P.
o See the open command.
close Closes the current open file, marking the next open file as
current (if one exists).
c See the close command.
chmod -r | -w
Change the mode of the currently open file. The -r option
will set the file permissions to read-only (0444), whilst
the -w option will set the file permissions to read-write
(0644). This allows xfs_io to set up mismatches between the
file permissions and the open file descriptor read/write
mode to exercise permission checks inside various syscalls.
pread [ -b bsize ] [ -qv ] [ -FBR [ -Z seed ] ] [ -V vectors ]
offset length
Reads a range of bytes in a specified blocksize from the
given offset.
-b can be used to set the blocksize into which the
read(2) requests will be split. The default
blocksize is 4096 bytes.
-q quiet mode, do not write anything to standard
output.
-v dump the contents of the buffer after reading, by
default only the count of bytes actually read is
dumped.
-F read the buffers in a forward sequential direction.
-B read the buffers in a reverse sequential direction.
-R read the buffers in the give range in a random
order.
-Z seed
specify the random number seed used for random
reads.
-V vectors
Use the vectored IO read syscall preadv(2) with a
number of blocksize length iovecs. The number of
iovecs is set by the vectors parameter.
r See the pread command.
pwrite [ -i file ] [ -qAdDwNOW ] [ -s skip ] [ -b size ] [ -S seed
] [ -FBR [ -Z zeed ] ] [ -V vectors ] offset length
Writes a range of bytes in a specified blocksize from the
given offset. The bytes written can be either a set
pattern or read in from another file before writing.
-i allows an input file to be specified as the source
of the data to be written.
-q quiet mode, do not write anything to standard
output.
-d causes direct I/O, rather than the usual buffered
I/O, to be used when reading the input file.
-w call fdatasync(2) once all writes are complete
(included in timing results)
-N Perform the pwritev2(2) call with RWF_NOWAIT.
-D Perform the pwritev2(2) call with RWF_DSYNC.
-A Perform the pwritev2(2) call with RWF_ATOMIC.
-O perform pwrite once and return the (maybe partial)
bytes written.
-W call fsync(2) once all writes are complete (included
in timing results)
-s specifies the number of bytes to skip from the start
of the input file before starting to read.
-b used to set the blocksize into which the write(2)
requests will be split. The default blocksize is
4096 bytes.
-S used to set the (repeated) fill pattern which is
used when the data to write is not coming from a
file. The default buffer fill pattern value is
0xcdcdcdcd.
-F write the buffers in a forward sequential direction.
-B write the buffers in a reverse sequential direction.
-R write the buffers in the give range in a random
order.
-Z seed
specify the random number seed used for random write
-V vectors
Use the vectored IO write syscall pwritev(2) with a
number of blocksize length iovecs. The number of
iovecs is set by the vectors parameter.
w See the pwrite command.
bmap [ -adelpv ] [ -n nx ]
Prints the block mapping for the current open file. Refer
to the xfs_bmap(8) manual page for complete documentation.
fiemap [ -alv ] [ -n nx ] [ offset [ len ]]
Prints the block mapping for the current open file using
the fiemap ioctl. Options behave as described in the
xfs_bmap(8) manual page.
Optionally, this command also supports passing the start
offset from where to begin the mapping and the length of
that region. The kernel will return any full extents which
intersect with the requested range, and the fiemap command
will print them in their entirety. If the requested range
starts or ends in a hole, fiemap will print the hole,
truncated to the requested range.
extsize [ -R | -D ] [ value ]
Display and/or modify the preferred extent size used when
allocating space for the currently open file. If the -R
option is specified, a recursive descent is performed for
all directory entries below the currently open file (-D can
be used to restrict the output to directories only). If
the target file is a directory, then the inherited extent
size is set for that directory (new files created in that
directory inherit that extent size). The value should be
specified in bytes, or using one of the usual units
suffixes (k, m, g, b, etc). The extent size is always
reported in units of bytes.
cowextsize [ -R | -D ] [ value ]
Display and/or modify the preferred copy-on-write extent
size used when allocating space for the currently open
file. If the -R option is specified, a recursive descent is
performed for all directory entries below the currently
open file (-D can be used to restrict the output to
directories only). If the target file is a directory, then
the inherited CoW extent size is set for that directory
(new files created in that directory inherit that CoW
extent size). The value should be specified in bytes, or
using one of the usual units suffixes (k, m, g, b, etc).
The extent size is always reported in units of bytes.
allocsp size 0
Sets the size of the file to size and zeroes any additional
space allocated using the XFS_IOC_ALLOCSP/XFS_IOC_FREESP
system call described in the xfsctl(3) manual page.
allocsp and freesp do exactly the same thing.
These commands are no longer supported as of Linux 5.17.
freesp size 0
See the allocsp command.
fadvise [ -r | -s | [[ -d | -n | -w ] offset length ]]
On platforms which support it, allows hints be given to the
system regarding the expected I/O patterns on the file.
The range arguments are required by some advise commands
([*] below), and the others must have no range arguments.
With no arguments, the POSIX_FADV_NORMAL advice is implied
(default readahead).
-d the data will not be accessed again in the near
future (POSIX_FADV_DONTNEED[*]).
-n data will be accessed once and not be reused
(POSIX_FADV_NOREUSE[*]).
-r expect access to data in random order
(POSIX_FADV_RANDOM), which sets readahead to zero.
-s expect access to data in sequential order
(POSIX_FADV_SEQUENTIAL), which doubles the default
readahead on the file.
-w advises the specified data will be needed again
(POSIX_FADV_WILLNEED[*]) which forces the maximum
readahead.
fdatasync
Calls fdatasync(2) to flush the file's in-core data to
disk.
fsync Calls fsync(2) to flush all in-core file state to disk.
s See the fsync command.
sync_range [ -a | -b | -w ] offset length
On platforms which support it, allows control of syncing a
range of the file to disk. With no options,
SYNC_FILE_RANGE_WRITE is implied on the range supplied.
-a wait for IO in the given range to finish after
writing (SYNC_FILE_RANGE_WAIT_AFTER).
-b wait for IO in the given range to finish before
writing (SYNC_FILE_RANGE_WAIT_BEFORE).
-w start writeback of dirty data in the given range
(SYNC_FILE_RANGE_WRITE).
sync Calls sync(2) to flush all filesystems' in-core data to
disk.
syncfs Calls syncfs(2) to flush this filesystem's in-core data to
disk.
resvsp offset length
Allocates reserved, unwritten space for part of a file
using the XFS_IOC_RESVSP system call described in the
xfsctl(3) manual page.
unresvsp offset length
Frees reserved space for part of a file using the
XFS_IOC_UNRESVSP system call described in the xfsctl(3)
manual page.
falloc [ -k ] offset length
Allocates reserved, unwritten space for part of a file
using the fallocate routine as described in the
fallocate(2) manual page.
-k will set the FALLOC_FL_KEEP_SIZE flag as described
in fallocate(2).
fcollapse offset length
Call fallocate with FALLOC_FL_COLLAPSE_RANGE flag as
described in the fallocate(2) manual page to de-allocates
blocks and eliminates the hole created in this process by
shifting data blocks into the hole.
finsert offset length
Call fallocate with FALLOC_FL_INSERT_RANGE flag as
described in the fallocate(2) manual page to create the
hole by shifting data blocks.
fpunch offset length
Punches (de-allocates) blocks in the file by calling
fallocate with the FALLOC_FL_PUNCH_HOLE flag as described
in the fallocate(2) manual page.
funshare offset length
Call fallocate with FALLOC_FL_UNSHARE_RANGE flag as
described in the fallocate(2) manual page to unshare all
shared blocks within the range.
fzero [ -k ] offset length
Call fallocate with FALLOC_FL_ZERO_RANGE flag as described
in the fallocate(2) manual page to allocate and zero blocks
within the range. With the -k option, use the
FALLOC_FL_KEEP_SIZE flag as well.
zero offset length
Call xfsctl with XFS_IOC_ZERO_RANGE as described in the
xfsctl(3) manual page to allocate and zero blocks within
the range.
truncate offset
Truncates the current file at the given offset using
ftruncate(2).
sendfile [ -q ] -i srcfile | -f N [ offset length ]
On platforms which support it, allows a direct in-kernel
copy between two file descriptors. The current open file is
the target, the source must be specified as another open
file (-f) or by path (-i).
-q quiet mode, do not write anything to standard output.
readdir [ -v ] [ -o offset ] [ -l length ]
Read a range of directory entries from a given offset of a
directory.
-v verbose mode - dump dirent content as defined in
readdir(3)
-o specify starting offset
-l specify total length to read (in bytes)
seek -a | -d | -h [ -r ] [ -s ] offset
On platforms that support the lseek(2) SEEK_DATA and
SEEK_HOLE options, display the offsets of the specified
segments.
-a Display both data and hole segments starting at the
specified offset.
-d Display the data segment starting at the specified
offset.
-h Display the hole segment starting at the specified
offset.
-r Recursively display all the specified segments
starting at the specified offset.
-s Display the starting lseek(2) offset. This offset
will be a calculated value when both data and holes
are displayed together or performing a recusively
display.
reflink [ -C ] [ -q ] src_file [src_offset dst_offset length]
On filesystems that support the FICLONERANGE or
BTRFS_IOC_CLONE_RANGE ioctls, map length bytes at offset
dst_offset in the open file to the same physical blocks
that are mapped at offset src_offset in the file src_file ,
replacing any contents that may already have been there.
If a program writes into a reflinked block range of either
file, the dirty blocks will be cloned, written to, and
remapped ("copy on write") in the affected file, leaving
the other file(s) unchanged. If src_offset, dst_offset,
and length are omitted, all contents of src_file will be
reflinked into the open file.
-C Print timing statistics in a condensed format.
-q Do not print timing statistics at all.
dedupe [ -C ] [ -q ] src_file src_offset dst_offset length
On filesystems that support the FIDEDUPERANGE or
BTRFS_IOC_FILE_EXTENT_SAME ioctls, map length bytes at
offset dst_offset in the open file to the same physical
blocks that are mapped at offset src_offset in the file
src_file , but only if the contents of both ranges are
identical. This is known as block-based deduplication. If
a program writes into a reflinked block range of either
file, the dirty blocks will be cloned, written to, and
remapped ("copy on write") in the affected file, leaving
the other file(s) unchanged.
-C Print timing statistics in a condensed format.
-q Do not print timing statistics at all.
copy_range [ -s src_offset ] [ -d dst_offset ] [ -l length ]
src_file | -f N
On filesystems that support the copy_file_range(2) system
call, copies data from the source file into the current
open file. The source must be specified either by path
(src_file) or as another open file (-f). If length is not
specified, this command copies data from src_offset to the
end of src_file into the dst_file at dst_offset.
-s Copy data from src_file beginning from src_offset.
-d Copy data into the open file beginning at
dst_offset.
-l Copy up to length bytes of data.
swapext donor_file
Swaps extent forks between files. The current open file is
the target. The donor file is specified by path. Note that
file data is not copied (file content moves with the
fork(s)).
exchangerange [OPTIONS]donor_file
Exchanges contents between files. The current open file is
the target. The donor file is specified by path. Note
that file data is not copied (file content moves with the
fork(s)). Options include:
-C Print timing information in a condensed format.
-c Exchange contents only if file2 has not changed.
-d dest_offset
Swap extents with open file beginning at
dest_offset.
-f Flush changed file data and file metadata to disk.
-l length
Swap up to length bytes of data.
-n Perform all the parameter validation checks but
don't change anything.
-s src_offset
Swap extents with donor file beginning at
src_offset.
-t Print timing information.
-w Only exchange written ranges in the supplied file.
set_encpolicy [ -c mode ] [ -n mode ] [ -f flags ] [ -s
log2_dusize ] [ -v version ] [ keyspec ]
On filesystems that support encryption, assign an
encryption policy to the current file. keyspec is a hex
string which specifies the encryption key to use. For v1
encryption policies, keyspec must be a 16-character hex
string (8 bytes). For v2 policies, keyspec must be a
32-character hex string (16 bytes). If unspecified, an
all-zeroes value is used.
-c mode
contents encryption mode (e.g. AES-256-XTS)
-n mode
filenames encryption mode (e.g. AES-256-CTS)
-f flags
policy flags (numeric)
-s log2_dusize
log2 of data unit size. Not supported by v1
policies.
-v version
policy version. Defaults to 1 or 2 depending on the
length of keyspec; or to 1 if keyspec is
unspecified.
get_encpolicy [ -1 ] [ -t ]
On filesystems that support encryption, display the
encryption policy of the current file.
-1 Use only the old ioctl to get the encryption policy.
This only works if the file has a v1 encryption
policy.
-t Test whether v2 encryption policies are supported.
Prints "supported", "unsupported", or an error
message.
add_enckey [ -d descriptor ] [ -k key_id ]
On filesystems that support encryption, add an encryption
key to the filesystem containing the currently open file.
By default, the raw key in binary (typically 64 bytes long)
is read from standard input.
-d descriptor
key descriptor, as a 16-character hex string (8
bytes). If given, the key will be available for use
by v1 encryption policies that use this descriptor.
Otherwise, the key is added as a v2 policy key, and
on success the resulting "key identifier" will be
printed.
-k key_id
ID of kernel keyring key of type "fscrypt-
provisioning". If given, the raw key will be taken
from here rather than from standard input.
rm_enckey [ -a ] keyspec
On filesystems that support encryption, remove an
encryption key from the filesystem containing the currently
open file. keyspec is a hex string specifying the key to
remove, as a 16-character "key descriptor" or a
32-character "key identifier".
-a Remove the key for all users who have added it, not
just the current user. This is a privileged
operation.
enckey_status keyspec
On filesystems that support encryption, display the status
of an encryption key. keyspec is a hex string specifying
the key for which to display the status, as a 16-character
"key descriptor" or a 32-character "key identifier".
lsattr [ -R | -D | -a | -v ]
List extended inode flags on the currently open file. If
the -R option is specified, a recursive descent is
performed for all directory entries below the currently
open file (-D can be used to restrict the output to
directories only). This is a depth first descent, it does
not follow symlinks and it also does not cross mount
points.
The current inode flag letters are documented below.
Please refer to the ioctl_xfs_fsgetxattr(2) documentation
for more details about what they mean.
r realtime file (XFS_XFLAG_REALTIME)
p prealloc (XFS_XFLAG_PREALLOC)
i immutable (XFS_XFLAG_IMMUTABLE)
a append only (XFS_XFLAG_APPEND)
s synchronous file writes (XFS_XFLAG_SYNC)
A noatime (XFS_XFLAG_NOATIME)
d nodump (XFS_XFLAG_NODUMP)
t inherit realtime flag (XFS_XFLAG_RTINHERIT)"
P inherit project id (XFS_XFLAG_PROJINHERIT)
n no symlink creation (XFS_XFLAG_NOSYMLINKS)
e extent size hint (XFS_XFLAG_EXTSIZE)
E inherit extent size hint (XFS_XFLAG_EXTSZINHERIT)
f nodefrag (XFS_XFLAG_NODEFRAG)
S filestream allocator (XFS_XFLAG_FILESTREAM)
x direct access persistent memory (XFS_XFLAG_DAX)
C copy on write extent hint (XFS_XFLAG_COWEXTSIZE)
X has extended attributes (XFS_XFLAG_HASATTR)
chattr [ -R | -D ] [ +/-riasAdtPneEfSxC ]
Change extended inode flags on the currently open file. The
-R and -D options have the same meaning as above.
See the lsattr command above for the list of inode flag
letters.
flink path
Link the currently open file descriptor into the filesystem
namespace.
stat [ -v|-r ]
Selected statistics from stat(2) and the XFS_IOC_GETXATTR
system call on the current file. If the -v option is
specified, the atime (last access), mtime (last modify),
and ctime (last change) timestamps are also displayed. The
-r option dumps raw fields from the stat structure.
statx [ -v|-r ][ -m basic | -m all | -m <mask> ][ -FD ]
Selected statistics from stat(2) and the XFS_IOC_GETXATTR
system call on the current file.
-v Show timestamps.
-r Dump raw statx structure values.
-m basic
Set the field mask for the statx call to
STATX_BASIC_STATS.
-m all
Set the the field mask for the statx call to
STATX_ALL (default).
-m <mask>
Specify a numeric field mask for the statx call.
-F Force the attributes to be synced with the server.
-D Don't sync attributes with the server.
chproj [ -R|-D ]
Modifies the project identifier associated with the current
path. The -R option will recursively descend if the current
path is a directory. The -D option will also recursively
descend, only setting modifying projects on subdirectories.
See the xfs_quota(8) manual page for more information about
project identifiers.
lsproj [ -R|-D ]
Displays the project identifier associated with the current
path. The -R and -D options behave as described above, in
chproj.
parent [ -fpz ] [ -b bufsize ] [ -i ino ] [ -n name ] [ ino gen ]
By default this command prints out the parent inode
numbers, inode generation numbers and basenames of all the
hardlinks which point to the inode of the current file.
If the optional ino and gen parameters are provided, they
will be used to create a file handle on the same filesystem
as the open file. The parents of the file represented by
the handle will be reported instead of the open file.
-b Use a buffer of this size to receive parent pointer
records from the kernel.
-i Only show parent pointer records containing this
inode number.
-n Only show parent pointer records containing this
directory entry name.
-p the output is similar to the default output except
pathnames up to the mount-point are printed out
instead of the component name.
-s Print records in short format: ino/gen/namelen/name
-z Print only the first path from the root.
utimes atime_sec atime_nsec mtime_sec mtime_nsec
The utimes command changes the atime and mtime of the
current file. sec uses UNIX timestamp notation and is the
seconds elapsed since 1970-01-01 00:00:00 UTC. nsec is the
nanoseconds since the sec. This value needs to be in the
range 0-999999999 with UTIME_NOW and UTIME_OMIT being
exceptions. Each (sec, nsec) pair constitutes a single
timestamp value.
startupdate [ -e]
Create a temporary clone of a file in which to stage file
updates. The -e option creates an empty staging file.
cancelupdate
Abandon changes from a update staging file.
commitupdate [OPTIONS]
Commit changes from a update staging file to the real file.
-C Print timing information in a condensed format.
-h Only swap ranges in the update staging file that
were actually written.
-k Do not change file size.
-n Check parameters without changing anything.
-q Do not print timing information at all.
mmap [ N | [[ -rwxS ] [-s size ] offset length ]]
With no arguments, mmap shows the current mappings.
Specifying a single numeric argument N sets the current
mapping. If two arguments are specified (a range specified
by offset and length), a new mapping is created spanning
the range, and the protection mode can be given as a
combination of PROT_READ (-r), PROT_WRITE (-w), and
PROT_EXEC (-x). The mapping will be created with the
MAP_SHARED flag by default, or with the Linux specific
(MAP_SYNC | MAP_SHARED_VALIDATE) flags if -S is given. -s
size is used to do a mmap(size) && munmap(size) operation
at first, try to reserve some extendible free memory space,
if size is bigger than length parameter. But there's not
guarantee that the memory after length ( up to size ) will
stay free. e.g. "mmap -rw -s 8192 1024" will mmap 0 ~
1024 bytes memory, but try to reserve 1024 ~ 8192 free
space(no guarantee). This free space will helpful for
"mremap 8192" without MREMAP_MAYMOVE flag.
mm See the mmap command.
mremap [ -f <new_address> ] [ -m ] new_length
Changes the current mapping size to new_length. Whether
the mapping may be moved is controlled by the flags passed;
MREMAP_FIXED (-f), or MREMAP_MAYMOVE (-m). new_length
specifies a page-aligned address to which the mapping must
be moved. It can be set to 139946004389888, 4096k or 1g
etc.
mrm See the mremap command.
munmap Unmaps the current memory mapping.
mu See the munmap command.
mread [ -f | -v ] [ -r ] [ offset length ]
Accesses a segment of the current memory mapping,
optionally dumping it to the standard output stream (with
-v or -f option) for inspection. The accesses are performed
sequentially from the start offset by default, but can also
be done from the end backwards through the mapping if the
-r option in specified. The two verbose modes differ only
in the relative offsets they display, the -f option is
relative to file start, whereas -v shows offsets relative
to the start of the mapping.
mr See the mread command.
mwrite [ -r ] [ -S seed ] [ offset length ]
Stores a byte into memory for a range within a mapping.
The default stored value is 'X', repeated to fill the range
specified, but this can be changed using the -S option.
The memory stores are performed sequentially from the start
offset by default, but can also be done from the end
backwards through the mapping if the -r option in
specified.
mw See the mwrite command.
msync [ -i ] [ -a | -s ] [ offset length ]
Writes all modified copies of pages over the specified
range (or entire mapping if no range specified) to their
backing storage locations. Also, optionally invalidates
(-i) so that subsequent references to the pages will be
obtained from their backing storage locations (instead of
cached copies). The flush can be done synchronously (-s)
or asynchronously (-a).
ms See the msync command.
madvise [ -d | -r | -s | -w ] [ offset length ]
Modifies page cache behavior when operating on the current
mapping. The range arguments are required by some advise
commands ([*] below). With no arguments, the
POSIX_MADV_NORMAL advice is implied (default readahead).
-d the pages will not be needed
(POSIX_MADV_DONTNEED[*]).
-r expect random page references (POSIX_MADV_RANDOM),
which sets readahead to zero.
-s expect sequential page references
(POSIX_MADV_SEQUENTIAL), which doubles the default
readahead on the file.
-w advises the specified pages will be needed again
(POSIX_MADV_WILLNEED[*]) which forces the maximum
readahead.
mincore
Dumps a list of pages or ranges of pages that are currently
in core, for the current memory mapping.
bulkstat [ -a agno ] [ -d ] [ -e endino ] [ -n batchsize ] [ -q ]
[ -s startino ] [ -v version"]
Display raw stat information about a bunch of inodes in an
XFS filesystem. Options are as follows:
-a agno
Display only results from the given allocation
group. If not specified, all results returned
will be displayed.
-d Print debugging information about call results.
-e endino
Stop displaying records when this inode number is
reached. Defaults to stopping when the system
call stops returning results.
-n batchsize
Retrieve at most this many records per call.
Defaults to 4,096.
-q Run quietly. Does not parse or output retrieved
bulkstat information.
-s startino
Display inode allocation records starting with
this inode. Defaults to the first inode in the
filesystem. If the given inode is not allocated,
results will begin with the next allocated inode
in the filesystem.
-v version
Use a particular version of the kernel interface.
Currently supported versions are 1 and 5.
bulkstat_single [ -d ] [ -v version ] [ inum... | special... ]
Display raw stat information about individual inodes in an
XFS filesystem. The -d and -v options are the same as the
bulkstat command. Arguments must be inode numbers or any
of the special values:
root Display information about the root directory
inode.
freeze Suspend all write I/O requests to the filesystem of the
current file. Only available in expert mode and requires
privileges.
thaw Undo the effects of a filesystem freeze operation. Only
available in expert mode and requires privileges.
inject [ tag ]
Inject errors into a filesystem to observe filesystem
behavior at specific points under adverse conditions.
Without the tag argument, displays the list of error tags
available. Only available in expert mode and requires
privileges.
resblks [ blocks ]
Get and/or set count of reserved filesystem blocks using
the XFS_IOC_GET_RESBLKS or XFS_IOC_SET_RESBLKS system
calls. Note -- this can be useful for exercising out of
space behavior. Only available in expert mode and requires
privileges.
shutdown [ -f ]
Force the filesystem to shut down, preventing any further
IO. XFS and other filesystems implement this
functionality, although implementation details may differ
slightly. Only available in expert mode and requires
privileges.
By default, the filesystem will not attempt to flush
completed transactions to disk before shutting down the
filesystem. This simulates a disk failure or crash.
-f Force the filesystem to flush all completed
transactions to disk before shutting down, matching
XFS behavior when critical corruption is
encountered.
statfs [ -c ] [ -g ] [ -s ]
Report selected statistics on the filesystem where the
current file resides. The default behavior is to enable
all three reporting options:
-c Display XFS_IOC_FSCOUNTERS summary counter data.
-g Display XFS_IOC_FSGEOMETRY filesystem geometry
data.
-s Display statfs(2) data.
inode [ [ -n ] number ] [ -v ]
The inode command queries physical information about an
inode. With no arguments, it will return 1 or 0, indicating
whether or not any inode numbers greater than 32 bits are
currently in use in the filesystem. If given an inode
number as an argument, the command will return the same
inode number if it is in use, or 0 if not. With -n number ,
the next used inode number after this number will be
returned, or zero if the supplied inode number is the
highest one in use. With -v the command will also report
the number of bits (32 or 64) used by the inode number
printed in the result; if no inode number was specified on
the command line, the maximum possible inode number in the
system will be printed along with its size.
inumbers [ -a agno ] [ -d ] [ -e endino ] [ -n batchsize ] [ -s
startino ] [ -v version ]
Prints allocation information about groups of inodes in an
XFS filesystem. Callers can use this information to figure
out which inodes are allocated. Options are as follows:
-a agno
Display only results from the given allocation
group. If not specified, all results returned
will be displayed.
-d Print debugging information about call results.
-e endino
Stop displaying records when this inode number is
reached. Defaults to stopping when the system
call stops returning results.
-n batchsize
Retrieve at most this many records per call.
Defaults to 4,096.
-s startino
Display inode allocation records starting with
this inode. Defaults to the first inode in the
filesystem. If the given inode is not allocated,
results will begin with the next allocated inode
in the filesystem.
-v version
Use a particular version of the kernel interface.
Currently supported versions are 1 and 5.
scrub type [ agnumber | ino gen ]
Scrub internal XFS filesystem metadata. The type parameter
specifies which type of metadata to scrub. For AG
metadata, one AG number must be specified. For file
metadata, the scrub is applied to the open file unless the
inode number and generation number are specified.
scrubv [ -b NN ] [ -d ] [ -m oflags ] [ -r ] [ -v NN ] [ -w ms ]
group [ agnumber | ino gen ]
Scrub a bunch of internal XFS filesystem metadata. The
group parameter specifies which group of metadata to scrub.
Valid groups are ag, agheader, inode, iscan, fs, probe,
rtgroup, or summary.
For ag and agheader metadata, one AG number must be
specified. For inode metadata, the scrub is applied to the
open file unless the inode number and generation number are
specified. For rtgroup metadata, one rt group number must
be specified.
-b NN Inject scrub barriers into the vector stream at
the given interval. Barriers abort vector
processing if any previous scrub function found
corruption.
-d Enables debug mode.
-m Fail scrub barriers if any of these scrub output
flags are seen.
-r Repair metadata if corruptions are found. This
option requires expert mode.
-v NN Force a particular API version. single selects
XFS_SCRUB_METADATA (one-by-one). vector selects
XFS_SCRUBV_METADATA (vectored). If no option is
specified, vector mode will be used, with a
fallback to single mode if the kernel doesn't
recognize the vector mode ioctl.
-w us Wait the given number of microseconds between
each scrub function.
repair type [ agnumber | ino gen ]
Repair internal XFS filesystem metadata. The type
parameter specifies which type of metadata to repair. For
AG metadata, one AG number must be specified. For file
metadata, the repair is applied to the open file unless the
inode number and generation number are specified. The -R
option can be specified to force rebuilding of a metadata
structure.
label [ -c | -s label ]
On filesystems that support online label manipulation, get,
set, or clear the filesystem label. With no options, print
the current filesystem label. The -c option clears the
filesystem label by setting it to the null string. The -s
label option sets the filesystem label to label. If the
label is longer than the filesystem will accept, xfs_io
will print an error message. XFS filesystem labels can be
at most 12 characters long.
fsmap [ -d | -l | -r ] [ -m | -v ] [ -n nx ] [ start ] [ end ]
Prints the mapping of disk blocks used by the filesystem
hosting the current file. The map lists each extent used
by files, allocation group metadata, journalling logs, and
static filesystem metadata, as well as any regions that are
unused. Each line of the listings takes the following
form:
extent: major:minor [startblock..endblock]: owner
startoffset..endoffset length
Static filesystem metadata, allocation group metadata,
btrees, journalling logs, and free space are marked by
replacing the startoffset..endoffset with the appropriate
marker. All blocks, offsets, and lengths are specified in
units of 512-byte blocks, no matter what the filesystem's
block size is. The optional start and end arguments can be
used to constrain the output to a particular range of disk
blocks. If these two options are specified, exactly one of
-d, -l, or -r must also be set.
-d Display only extents from the data device. This
option only applies for XFS filesystems.
-l Display only extents from the external log
device. This option only applies to XFS
filesystems.
-r Display only extents from the realtime device.
This option only applies to XFS filesystems.
-m Display results in a machine readable format
(CSV). This option is not compatible with the -v
flag. The columns of the output are: extent
number, device major, device minor, physical
start, physical end, owner, offset start, offset
end, length. The start, end, and length numbers
are provided in units of 512b. The owner field
is a special string that takes the form:
inode_%lld_data
for inode data.
inode_%lld_data_bmbt
for inode data extent maps.
inode_%lld_attr
for inode extended attribute data.
inode_%lld_attr_bmbt
for inode extended attribute extent maps.
special_%u:%u
for other filesystem metadata.
-n num_extents
If this option is given, fsmap obtains the extent
list of the file in groups of num_extents
extents. In the absence of -n, fsmap queries the
system for extents in groups of 131,072 records.
-v Shows verbose information. When this flag is
specified, additional AG specific information is
appended to each line in the following form:
agno (startagblock..endagblock) nblocks
flags
A second -v option will print out the flags
legend. This option is not compatible with the
-m flag.
fsuuid Print the mounted filesystem UUID.
sysfspath
Print the sysfs or debugfs path for the mounted filesystem.
The -d option selects debugfs instead of sysfs.
getfsprops name [ names... ]
Retrieve the values of the given filesystem properties.
listfsprops [ -v ]
List all filesystem properties that have been stored in the
filesystem. If the -v flag is specified, prints the values
of the properties.
setfsprops name=value [ name=value... ]
Set the given filesystem properties to the specified
values.
removefsprops name [ names... ]
Remove the given filesystem properties.
help [ command ]
Display a brief description of one or all commands.
print Display a list of all open files and memory mapped regions.
The current file and current mapping are distinguishable
from any others.
p See the print command.
quit Exit xfs_io.
q See the quit command.
log_writes -d device -m mark
Create a mark named mark in the dm-log-writes log specified
by device. This is intended to be equivalent to the shell
command:
dmsetup message device 0 mark mark
lw See the log_writes command.
crc32cselftest
Test the internal crc32c implementation to make sure that
it computes results correctly.
mkfs.xfs(8), xfsctl(3), xfs_bmap(8), xfs_db(8), xfs(5),
fdatasync(2), fstat(2), fstatfs(2), fsync(2), ftruncate(2),
futimens(3), mmap(2), msync(2), open(2), pread(2), pwrite(2),
readdir(3), dmsetup(8).
This page is part of the xfsprogs (utilities for XFS filesystems)
project. Information about the project can be found at
⟨http://xfs.org/⟩. If you have a bug report for this manual page,
send it to linux-xfs@vger.kernel.org. This page was obtained from
the project's upstream Git repository
⟨https://git.kernel.org/pub/scm/fs/xfs/xfsprogs-dev.git⟩ on
2025-02-02. (At that time, the date of the most recent commit
that was found in the repository was 2024-12-02.) If you discover
any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page,
or you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a
mail to man-pages@man7.org
xfs_io(8)
Pages that refer to this page: xfs_fsr(8)
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