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authorDavid Sterba <dsterba@suse.com>2016-01-11 15:28:08 +0100
committerDavid Sterba <dsterba@suse.com>2016-01-12 15:02:53 +0100
commita8829f5335a121928cf773ba00be4530bf0267c0 (patch)
treee24c588bc6d78c4a8e745dbd5062644a0bf2bf64 /Documentation
parent7ccc0543dc25cd5751f500dd58df766d61b43095 (diff)
btrfs-progs: docs, btrfs-mount: enhance file attributes section
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/btrfs-mount.asciidoc57
1 files changed, 43 insertions, 14 deletions
diff --git a/Documentation/btrfs-mount.asciidoc b/Documentation/btrfs-mount.asciidoc
index 8be70e33..aa253824 100644
--- a/Documentation/btrfs-mount.asciidoc
+++ b/Documentation/btrfs-mount.asciidoc
@@ -8,7 +8,11 @@ btrfs-mount - topics about the BTRFS filesystem (mount options, supported file a
DESCRIPTION
-----------
This document describes topics related to BTRFS that are not specific to the
-tools.
+tools. Currently covers:
+
+1. mount options
+
+2. file attributes
MOUNT OPTIONS
-------------
@@ -332,29 +336,54 @@ root user can do that.
FILE ATTRIBUTES
---------------
-The btrfs filesystem supports setting the following file
-attributes the `chattr`(1) utility
+The btrfs filesystem supports setting the following file attributes using the
+`chattr`(1) utility:
-*a* -- append only
+*a*::
+'append only', new writes are always written at the end of the file
-*A* -- no atime updates
+*A*::
+'no atime updates'
-*c* -- compressed
+*c*::
+'compress data', all data written after this attribute is set will be compressed.
+Please note that compression is also affected by the mount options or the parent
+directory attributes.
++
+When set on a directory, all newly created files will inherit this attribute.
-*C* -- no copy on write
+*C*::
+'no copy-on-write', file modifications are done in-place
++
+When set on a directory, all newly created files will inherit this attribute.
++
+NOTE: due to implementation limitations, this flag can be set/unset only on
+empty files.
-*d* -- no dump
+*d*::
+'no dump', makes sense with 3rd party tools like `dump`(8), on BTRFS the
+attribute can be set/unset on no other special handling is done
-*D* -- synchronous directory updates
+*D*::
+'synchronous directory updates', for more details search `open`(2) for 'O_SYNC'
+and 'O_DSYNC'
-*i* -- immutable
+*i*::
+'immutable', no file data and metadata changes allowed even to the root user as
+long as this attribute is set (obviously the exception is unsetting the attribute)
-*S* -- synchronous updates
+*S*::
+'synchronous updates', for more details search `open`(2) for 'O_SYNC' and
+'O_DSYNC'
-*X* -- no compression
+*X*::
+'no compression', permanently turn off compression on the given file, other
+compression mount options will not affect that
++
+When set on a directory, all newly created files will inherit this attribute.
-For descriptions of these attribute flags, please refer to the
-`chattr`(1) man page.
+No other attributes are supported. For the complete list please refer to the
+`chattr`(1) manual page.
SEE ALSO
--------