btrfs-progs: docs: sort mount options alphabetically
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba
parent
e4797df6a9
commit
23c51533ae
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@ -18,7 +18,15 @@ MOUNT OPTIONS
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-------------
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This section describes mount options specific to BTRFS. For the generic mount
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options please refer to `mount`(8) manpage.
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options please refer to `mount`(8) manpage. The options are sorted alphabetically
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(discarding the 'no' prefix).
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*acl*::
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*noacl*::
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(default: on)
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+
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Enable/disable support for Posix Access Control Lists (ACLs). See the
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`acl`(5) manual page for more information about ACLs.
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*alloc_start='bytes'*::
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(default: 1M, minimum: 1M)
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@ -50,6 +58,27 @@ copied with `cp --reflink`, snapshots or de-duplicated data).
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This may cause considerable increase of space usage depending on the
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broken up ref-links.
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*barrier*::
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*nobarrier*::
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(default: on)
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+
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Ensure that all IO write operations make it through the device cache and are stored
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permanently when the filesystem is at it's consistency checkpoint. This
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typically means that a flush command is sent to the device that will
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synchronize all pending data and ordinary metadata blocks, then writes the
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superblock and issues another flush.
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+
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The write flushes incur a slight hit and also prevent the IO block
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scheduler to reorder requests in more effective way. Disabling barriers gets
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rid of that penalty but will most certainly lead to a corrupted filesystem in
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case of a crash or power loss. The ordinary metadata blocks could be yet
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unwrittent at the time the new superblock is stored permanently, expecting that
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the block pointers to metadata were stored permanently before.
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+
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On a device with a volatile battery-backed write-back cache, the 'nobarrier'
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option will not lead to filesystem corruption as the pending blocks are
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supposed to make it to the permanent storage.
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*check_int*::
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*check_int_data*::
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*check_int_print_mask='value'*::
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@ -72,6 +101,10 @@ checker module behavior. +
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See comments at the top of 'fs/btrfs/check-integrity.c'
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for more info.
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*clear_cache*::
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Force clearing and rebuilding of the disk space cache if something
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has gone wrong. See also: 'space_cache'.
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*commit='seconds'*::
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(since: 3.12, default: 30)
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+
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@ -93,6 +126,23 @@ all files will be compressed, whether or not they compress well.
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+
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NOTE: If compression is enabled, 'nodatacow' and 'nodatasum' are disabled.
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*datacow*::
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*nodatacow*::
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(default: on)
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+
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Enable data copy-on-write for newly created files.
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'Nodatacow' implies 'nodatasum', and disables 'compression'. All files created
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under 'nodatacow' are also set the NOCOW file attribute (see `chattr`(1)).
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*datasum*::
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*nodatasum*::
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(default: on)
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+
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Enable data checksumming for newly created files.
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'Datasum' implies 'datacow', ie. the normal mode of operation. All files created
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under 'nodatasum' inherit the "no checksums" property, however there's no
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corresponding file attribute (see `chattr`(1)).
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*degraded*::
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(default: off)
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+
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@ -125,6 +175,7 @@ If discarding is not necessary to be done at the block freeing time, there's
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possibly not much interfering with other operations.
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*enospc_debug*::
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*noenospc_debug*::
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(default: off)
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+
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Enable verbose output for some ENOSPC conditions. It's safe to use but can
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@ -198,65 +249,6 @@ override the internal logic in favor of the metadata allocation if the expected
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workload is supposed to be metadata intense (snapshots, reflinks, xattrs,
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inlined files).
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*acl*::
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*noacl*::
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(default: on)
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+
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Enable/disable support for Posix Access Control Lists (ACLs). See the
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`acl`(5) manual page for more information about ACLs.
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*barrier*::
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*nobarrier*::
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(default: on)
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+
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Ensure that all IO write operations make it through the device cache and are stored
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permanently when the filesystem is at it's consistency checkpoint. This
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typically means that a flush command is sent to the device that will
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synchronize all pending data and ordinary metadata blocks, then writes the
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superblock and issues another flush.
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+
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The write flushes incur a slight hit and also prevent the IO block
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scheduler to reorder requests in more effective way. Disabling barriers gets
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rid of that penalty but will most certainly lead to a corrupted filesystem in
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case of a crash or power loss. The ordinary metadata blocks could be yet
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unwrittent at the time the new superblock is stored permanently, expecting that
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the block pointers to metadata were stored permanently before.
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+
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On a device with a volatile battery-backed write-back cache, the 'nobarrier'
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option will not lead to filesystem corruption as the pending blocks are
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supposed to make it to the permanent storage.
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*datacow*::
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*nodatacow*::
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(default: on)
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+
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Enable data copy-on-write for newly created files.
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'Nodatacow' implies 'nodatasum', and disables 'compression'. All files created
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under 'nodatacow' are also set the NOCOW file attribute (see `chattr`(1)).
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*datasum*::
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*nodatasum*::
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(default: on)
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+
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Enable data checksumming for newly created files.
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'Datasum' implies 'datacow', ie. the normal mode of operation. All files created
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under 'nodatasum' inherit the "no checksums" property, however there's no
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corresponding file attribute (see `chattr`(1)).
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*treelog*::
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*notreelog*::
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(default: on)
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+
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Enable the tree logging used for 'fsync' and 'O_SYNC' writes. The tree log
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stores changes without the need of a full filesystem sync. The log operations
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are flushed at sync and transaction commit. If the system crashes between two
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such syncs, the pending tree log operations are replayed during mount.
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+
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WARNING: currently, the tree log is replayed even with a read-only mount!
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+
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The tree log could contain new files/directories, these would not exist on
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a mounted filesystm if the log is not replayed.
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*recovery*::
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(since: 3.2, default: off)
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+
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@ -277,18 +269,15 @@ Skip automatic resume of interrupted balance operation after mount.
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May be resumed with *btrfs balance resume* or the paused state can be removed
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by *btrfs balance cancel*.
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*space_cache*::
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*nospace_cache*::
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(since: 3.2)
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('nospace_cache' since: 3.2, default: on)
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+
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Disable freespace cache loading without clearing the cache and the free space
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cache will not be used during the mount. This affects performance as searching
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for new free blocks could take longer. On the other hand, managing the space
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cache consumes some resources.
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*clear_cache*::
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Force clearing and rebuilding of the disk space cache if something
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has gone wrong.
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*ssd*::
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*nossd*::
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*ssd_spread*::
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@ -328,6 +317,20 @@ processing data and metadata, higher numbers could lead to a performance due to
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increased locking contention, cache-line bouncing or costly data transfers
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between local CPU memories.
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*treelog*::
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*notreelog*::
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(default: on)
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+
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Enable the tree logging used for 'fsync' and 'O_SYNC' writes. The tree log
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stores changes without the need of a full filesystem sync. The log operations
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are flushed at sync and transaction commit. If the system crashes between two
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such syncs, the pending tree log operations are replayed during mount.
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+
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WARNING: currently, the tree log is replayed even with a read-only mount!
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+
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The tree log could contain new files/directories, these would not exist on
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a mounted filesystm if the log is not replayed.
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*user_subvol_rm_allowed*::
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(default: off)
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+
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