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| -rw-r--r-- | Documentation/btrfs-mount.asciidoc | 57 |
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 -------- |