summaryrefslogtreecommitdiffstats
path: root/Documentation/filesystems
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2019-07-18 11:18:00 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-07-18 11:18:00 -0700
commit366a4e38b8d0d3e8c7673ab5c1b5e76bbfbc0085 (patch)
tree7008e59815214b760003707257bd06df46a55a9e /Documentation/filesystems
parentae9b728c8dc0a9939d89f84e8603258ca2a0df22 (diff)
parent89b408a68b9dd163b2705b6f73d8e3cc3579b457 (diff)
downloadlinux-366a4e38b8d0d3e8c7673ab5c1b5e76bbfbc0085.tar.bz2
Merge tag 'xfs-5.3-merge-13' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux
Pull xfs cleanups from Darrick Wong: "We had a few more lateish cleanup patches come in for 5.3 -- a couple of syncups with the userspace libxfs code and a conversion of the XFS administrator's guide to ReST format. Summary: - Bring fs/xfs/libxfs/xfs_trans_inode.c in sync with userspace libxfs. - Convert the xfs administrator guide to rst and move it into the official admin guide under Documentation" * tag 'xfs-5.3-merge-13' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: Documentation: filesystem: Convert xfs.txt to ReST xfs: sync up xfs_trans_inode with userspace xfs: move xfs_trans_inode.c to libxfs/
Diffstat (limited to 'Documentation/filesystems')
-rw-r--r--Documentation/filesystems/dax.txt2
-rw-r--r--Documentation/filesystems/xfs.txt470
2 files changed, 1 insertions, 471 deletions
diff --git a/Documentation/filesystems/dax.txt b/Documentation/filesystems/dax.txt
index 6d2c0d340dea..679729442fd2 100644
--- a/Documentation/filesystems/dax.txt
+++ b/Documentation/filesystems/dax.txt
@@ -76,7 +76,7 @@ exposure of uninitialized data through mmap.
These filesystems may be used for inspiration:
- ext2: see Documentation/filesystems/ext2.txt
- ext4: see Documentation/filesystems/ext4/
-- xfs: see Documentation/filesystems/xfs.txt
+- xfs: see Documentation/admin-guide/xfs.rst
Handling Media Errors
diff --git a/Documentation/filesystems/xfs.txt b/Documentation/filesystems/xfs.txt
deleted file mode 100644
index a5cbb5e0e3db..000000000000
--- a/Documentation/filesystems/xfs.txt
+++ /dev/null
@@ -1,470 +0,0 @@
-
-The SGI XFS Filesystem
-======================
-
-XFS is a high performance journaling filesystem which originated
-on the SGI IRIX platform. It is completely multi-threaded, can
-support large files and large filesystems, extended attributes,
-variable block sizes, is extent based, and makes extensive use of
-Btrees (directories, extents, free space) to aid both performance
-and scalability.
-
-Refer to the documentation at https://xfs.wiki.kernel.org/
-for further details. This implementation is on-disk compatible
-with the IRIX version of XFS.
-
-
-Mount Options
-=============
-
-When mounting an XFS filesystem, the following options are accepted.
-For boolean mount options, the names with the (*) suffix is the
-default behaviour.
-
- allocsize=size
- Sets the buffered I/O end-of-file preallocation size when
- doing delayed allocation writeout (default size is 64KiB).
- Valid values for this option are page size (typically 4KiB)
- through to 1GiB, inclusive, in power-of-2 increments.
-
- The default behaviour is for dynamic end-of-file
- preallocation size, which uses a set of heuristics to
- optimise the preallocation size based on the current
- allocation patterns within the file and the access patterns
- to the file. Specifying a fixed allocsize value turns off
- the dynamic behaviour.
-
- attr2
- noattr2
- The options enable/disable an "opportunistic" improvement to
- be made in the way inline extended attributes are stored
- on-disk. When the new form is used for the first time when
- attr2 is selected (either when setting or removing extended
- attributes) the on-disk superblock feature bit field will be
- updated to reflect this format being in use.
-
- The default behaviour is determined by the on-disk feature
- bit indicating that attr2 behaviour is active. If either
- mount option it set, then that becomes the new default used
- by the filesystem.
-
- CRC enabled filesystems always use the attr2 format, and so
- will reject the noattr2 mount option if it is set.
-
- discard
- nodiscard (*)
- Enable/disable the issuing of commands to let the block
- device reclaim space freed by the filesystem. This is
- useful for SSD devices, thinly provisioned LUNs and virtual
- machine images, but may have a performance impact.
-
- Note: It is currently recommended that you use the fstrim
- application to discard unused blocks rather than the discard
- mount option because the performance impact of this option
- is quite severe.
-
- grpid/bsdgroups
- nogrpid/sysvgroups (*)
- These options define what group ID a newly created file
- gets. When grpid is set, it takes the group ID of the
- directory in which it is created; otherwise it takes the
- fsgid of the current process, unless the directory has the
- setgid bit set, in which case it takes the gid from the
- parent directory, and also gets the setgid bit set if it is
- a directory itself.
-
- filestreams
- Make the data allocator use the filestreams allocation mode
- across the entire filesystem rather than just on directories
- configured to use it.
-
- ikeep
- noikeep (*)
- When ikeep is specified, XFS does not delete empty inode
- clusters and keeps them around on disk. When noikeep is
- specified, empty inode clusters are returned to the free
- space pool.
-
- inode32
- inode64 (*)
- When inode32 is specified, it indicates that XFS limits
- inode creation to locations which will not result in inode
- numbers with more than 32 bits of significance.
-
- When inode64 is specified, it indicates that XFS is allowed
- to create inodes at any location in the filesystem,
- including those which will result in inode numbers occupying
- more than 32 bits of significance.
-
- inode32 is provided for backwards compatibility with older
- systems and applications, since 64 bits inode numbers might
- cause problems for some applications that cannot handle
- large inode numbers. If applications are in use which do
- not handle inode numbers bigger than 32 bits, the inode32
- option should be specified.
-
-
- largeio
- nolargeio (*)
- If "nolargeio" is specified, the optimal I/O reported in
- st_blksize by stat(2) will be as small as possible to allow
- user applications to avoid inefficient read/modify/write
- I/O. This is typically the page size of the machine, as
- this is the granularity of the page cache.
-
- If "largeio" specified, a filesystem that was created with a
- "swidth" specified will return the "swidth" value (in bytes)
- in st_blksize. If the filesystem does not have a "swidth"
- specified but does specify an "allocsize" then "allocsize"
- (in bytes) will be returned instead. Otherwise the behaviour
- is the same as if "nolargeio" was specified.
-
- logbufs=value
- Set the number of in-memory log buffers. Valid numbers
- range from 2-8 inclusive.
-
- The default value is 8 buffers.
-
- If the memory cost of 8 log buffers is too high on small
- systems, then it may be reduced at some cost to performance
- on metadata intensive workloads. The logbsize option below
- controls the size of each buffer and so is also relevant to
- this case.
-
- logbsize=value
- Set the size of each in-memory log buffer. The size may be
- specified in bytes, or in kilobytes with a "k" suffix.
- Valid sizes for version 1 and version 2 logs are 16384 (16k)
- and 32768 (32k). Valid sizes for version 2 logs also
- include 65536 (64k), 131072 (128k) and 262144 (256k). The
- logbsize must be an integer multiple of the log
- stripe unit configured at mkfs time.
-
- The default value for for version 1 logs is 32768, while the
- default value for version 2 logs is MAX(32768, log_sunit).
-
- logdev=device and rtdev=device
- Use an external log (metadata journal) and/or real-time device.
- An XFS filesystem has up to three parts: a data section, a log
- section, and a real-time section. The real-time section is
- optional, and the log section can be separate from the data
- section or contained within it.
-
- noalign
- Data allocations will not be aligned at stripe unit
- boundaries. This is only relevant to filesystems created
- with non-zero data alignment parameters (sunit, swidth) by
- mkfs.
-
- norecovery
- The filesystem will be mounted without running log recovery.
- If the filesystem was not cleanly unmounted, it is likely to
- be inconsistent when mounted in "norecovery" mode.
- Some files or directories may not be accessible because of this.
- Filesystems mounted "norecovery" must be mounted read-only or
- the mount will fail.
-
- nouuid
- Don't check for double mounted file systems using the file
- system uuid. This is useful to mount LVM snapshot volumes,
- and often used in combination with "norecovery" for mounting
- read-only snapshots.
-
- noquota
- Forcibly turns off all quota accounting and enforcement
- within the filesystem.
-
- uquota/usrquota/uqnoenforce/quota
- User disk quota accounting enabled, and limits (optionally)
- enforced. Refer to xfs_quota(8) for further details.
-
- gquota/grpquota/gqnoenforce
- Group disk quota accounting enabled and limits (optionally)
- enforced. Refer to xfs_quota(8) for further details.
-
- pquota/prjquota/pqnoenforce
- Project disk quota accounting enabled and limits (optionally)
- enforced. Refer to xfs_quota(8) for further details.
-
- sunit=value and swidth=value
- Used to specify the stripe unit and width for a RAID device
- or a stripe volume. "value" must be specified in 512-byte
- block units. These options are only relevant to filesystems
- that were created with non-zero data alignment parameters.
-
- The sunit and swidth parameters specified must be compatible
- with the existing filesystem alignment characteristics. In
- general, that means the only valid changes to sunit are
- increasing it by a power-of-2 multiple. Valid swidth values
- are any integer multiple of a valid sunit value.
-
- Typically the only time these mount options are necessary if
- after an underlying RAID device has had it's geometry
- modified, such as adding a new disk to a RAID5 lun and
- reshaping it.
-
- swalloc
- Data allocations will be rounded up to stripe width boundaries
- when the current end of file is being extended and the file
- size is larger than the stripe width size.
-
- wsync
- When specified, all filesystem namespace operations are
- executed synchronously. This ensures that when the namespace
- operation (create, unlink, etc) completes, the change to the
- namespace is on stable storage. This is useful in HA setups
- where failover must not result in clients seeing
- inconsistent namespace presentation during or after a
- failover event.
-
-
-Deprecated Mount Options
-========================
-
- Name Removal Schedule
- ---- ----------------
-
-
-Removed Mount Options
-=====================
-
- Name Removed
- ---- -------
- delaylog/nodelaylog v4.0
- ihashsize v4.0
- irixsgid v4.0
- osyncisdsync/osyncisosync v4.0
- barrier v4.19
- nobarrier v4.19
-
-
-sysctls
-=======
-
-The following sysctls are available for the XFS filesystem:
-
- fs.xfs.stats_clear (Min: 0 Default: 0 Max: 1)
- Setting this to "1" clears accumulated XFS statistics
- in /proc/fs/xfs/stat. It then immediately resets to "0".
-
- fs.xfs.xfssyncd_centisecs (Min: 100 Default: 3000 Max: 720000)
- The interval at which the filesystem flushes metadata
- out to disk and runs internal cache cleanup routines.
-
- fs.xfs.filestream_centisecs (Min: 1 Default: 3000 Max: 360000)
- The interval at which the filesystem ages filestreams cache
- references and returns timed-out AGs back to the free stream
- pool.
-
- fs.xfs.speculative_prealloc_lifetime
- (Units: seconds Min: 1 Default: 300 Max: 86400)
- The interval at which the background scanning for inodes
- with unused speculative preallocation runs. The scan
- removes unused preallocation from clean inodes and releases
- the unused space back to the free pool.
-
- fs.xfs.error_level (Min: 0 Default: 3 Max: 11)
- A volume knob for error reporting when internal errors occur.
- This will generate detailed messages & backtraces for filesystem
- shutdowns, for example. Current threshold values are:
-
- XFS_ERRLEVEL_OFF: 0
- XFS_ERRLEVEL_LOW: 1
- XFS_ERRLEVEL_HIGH: 5
-
- fs.xfs.panic_mask (Min: 0 Default: 0 Max: 256)
- Causes certain error conditions to call BUG(). Value is a bitmask;
- OR together the tags which represent errors which should cause panics:
-
- XFS_NO_PTAG 0
- XFS_PTAG_IFLUSH 0x00000001
- XFS_PTAG_LOGRES 0x00000002
- XFS_PTAG_AILDELETE 0x00000004
- XFS_PTAG_ERROR_REPORT 0x00000008
- XFS_PTAG_SHUTDOWN_CORRUPT 0x00000010
- XFS_PTAG_SHUTDOWN_IOERROR 0x00000020
- XFS_PTAG_SHUTDOWN_LOGERROR 0x00000040
- XFS_PTAG_FSBLOCK_ZERO 0x00000080
- XFS_PTAG_VERIFIER_ERROR 0x00000100
-
- This option is intended for debugging only.
-
- fs.xfs.irix_symlink_mode (Min: 0 Default: 0 Max: 1)
- Controls whether symlinks are created with mode 0777 (default)
- or whether their mode is affected by the umask (irix mode).
-
- fs.xfs.irix_sgid_inherit (Min: 0 Default: 0 Max: 1)
- Controls files created in SGID directories.
- If the group ID of the new file does not match the effective group
- ID or one of the supplementary group IDs of the parent dir, the
- ISGID bit is cleared if the irix_sgid_inherit compatibility sysctl
- is set.
-
- fs.xfs.inherit_sync (Min: 0 Default: 1 Max: 1)
- Setting this to "1" will cause the "sync" flag set
- by the xfs_io(8) chattr command on a directory to be
- inherited by files in that directory.
-
- fs.xfs.inherit_nodump (Min: 0 Default: 1 Max: 1)
- Setting this to "1" will cause the "nodump" flag set
- by the xfs_io(8) chattr command on a directory to be
- inherited by files in that directory.
-
- fs.xfs.inherit_noatime (Min: 0 Default: 1 Max: 1)
- Setting this to "1" will cause the "noatime" flag set
- by the xfs_io(8) chattr command on a directory to be
- inherited by files in that directory.
-
- fs.xfs.inherit_nosymlinks (Min: 0 Default: 1 Max: 1)
- Setting this to "1" will cause the "nosymlinks" flag set
- by the xfs_io(8) chattr command on a directory to be
- inherited by files in that directory.
-
- fs.xfs.inherit_nodefrag (Min: 0 Default: 1 Max: 1)
- Setting this to "1" will cause the "nodefrag" flag set
- by the xfs_io(8) chattr command on a directory to be
- inherited by files in that directory.
-
- fs.xfs.rotorstep (Min: 1 Default: 1 Max: 256)
- In "inode32" allocation mode, this option determines how many
- files the allocator attempts to allocate in the same allocation
- group before moving to the next allocation group. The intent
- is to control the rate at which the allocator moves between
- allocation groups when allocating extents for new files.
-
-Deprecated Sysctls
-==================
-
-None at present.
-
-
-Removed Sysctls
-===============
-
- Name Removed
- ---- -------
- fs.xfs.xfsbufd_centisec v4.0
- fs.xfs.age_buffer_centisecs v4.0
-
-
-Error handling
-==============
-
-XFS can act differently according to the type of error found during its
-operation. The implementation introduces the following concepts to the error
-handler:
-
- -failure speed:
- Defines how fast XFS should propagate an error upwards when a specific
- error is found during the filesystem operation. It can propagate
- immediately, after a defined number of retries, after a set time period,
- or simply retry forever.
-
- -error classes:
- Specifies the subsystem the error configuration will apply to, such as
- metadata IO or memory allocation. Different subsystems will have
- different error handlers for which behaviour can be configured.
-
- -error handlers:
- Defines the behavior for a specific error.
-
-The filesystem behavior during an error can be set via sysfs files. Each
-error handler works independently - the first condition met by an error handler
-for a specific class will cause the error to be propagated rather than reset and
-retried.
-
-The action taken by the filesystem when the error is propagated is context
-dependent - it may cause a shut down in the case of an unrecoverable error,
-it may be reported back to userspace, or it may even be ignored because
-there's nothing useful we can with the error or anyone we can report it to (e.g.
-during unmount).
-
-The configuration files are organized into the following hierarchy for each
-mounted filesystem:
-
- /sys/fs/xfs/<dev>/error/<class>/<error>/
-
-Where:
- <dev>
- The short device name of the mounted filesystem. This is the same device
- name that shows up in XFS kernel error messages as "XFS(<dev>): ..."
-
- <class>
- The subsystem the error configuration belongs to. As of 4.9, the defined
- classes are:
-
- - "metadata": applies metadata buffer write IO
-
- <error>
- The individual error handler configurations.
-
-
-Each filesystem has "global" error configuration options defined in their top
-level directory:
-
- /sys/fs/xfs/<dev>/error/
-
- fail_at_unmount (Min: 0 Default: 1 Max: 1)
- Defines the filesystem error behavior at unmount time.
-
- If set to a value of 1, XFS will override all other error configurations
- during unmount and replace them with "immediate fail" characteristics.
- i.e. no retries, no retry timeout. This will always allow unmount to
- succeed when there are persistent errors present.
-
- If set to 0, the configured retry behaviour will continue until all
- retries and/or timeouts have been exhausted. This will delay unmount
- completion when there are persistent errors, and it may prevent the
- filesystem from ever unmounting fully in the case of "retry forever"
- handler configurations.
-
- Note: there is no guarantee that fail_at_unmount can be set while an
- unmount is in progress. It is possible that the sysfs entries are
- removed by the unmounting filesystem before a "retry forever" error
- handler configuration causes unmount to hang, and hence the filesystem
- must be configured appropriately before unmount begins to prevent
- unmount hangs.
-
-Each filesystem has specific error class handlers that define the error
-propagation behaviour for specific errors. There is also a "default" error
-handler defined, which defines the behaviour for all errors that don't have
-specific handlers defined. Where multiple retry constraints are configuredi for
-a single error, the first retry configuration that expires will cause the error
-to be propagated. The handler configurations are found in the directory:
-
- /sys/fs/xfs/<dev>/error/<class>/<error>/
-
- max_retries (Min: -1 Default: Varies Max: INTMAX)
- Defines the allowed number of retries of a specific error before
- the filesystem will propagate the error. The retry count for a given
- error context (e.g. a specific metadata buffer) is reset every time
- there is a successful completion of the operation.
-
- Setting the value to "-1" will cause XFS to retry forever for this
- specific error.
-
- Setting the value to "0" will cause XFS to fail immediately when the
- specific error is reported.
-
- Setting the value to "N" (where 0 < N < Max) will make XFS retry the
- operation "N" times before propagating the error.
-
- retry_timeout_seconds (Min: -1 Default: Varies Max: 1 day)
- Define the amount of time (in seconds) that the filesystem is
- allowed to retry its operations when the specific error is
- found.
-
- Setting the value to "-1" will allow XFS to retry forever for this
- specific error.
-
- Setting the value to "0" will cause XFS to fail immediately when the
- specific error is reported.
-
- Setting the value to "N" (where 0 < N < Max) will allow XFS to retry the
- operation for up to "N" seconds before propagating the error.
-
-Note: The default behaviour for a specific error handler is dependent on both
-the class and error context. For example, the default values for
-"metadata/ENODEV" are "0" rather than "-1" so that this error handler defaults
-to "fail immediately" behaviour. This is done because ENODEV is a fatal,
-unrecoverable error no matter how many times the metadata IO is retried.