btrfs-progs: docs: update wording for compression mount options

Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba 2017-07-24 16:45:40 +02:00
parent 5c2cf48a4c
commit 3b4927b558

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@ -120,10 +120,15 @@ but a warning is printed if it's more than 300 seconds (5 minutes).
Control BTRFS file data compression. Type may be specified as 'zlib',
'lzo' or 'no' (for no compression, used for remounting). If no type
is specified, 'zlib' is used. If 'compress-force' is specified,
all files will be compressed, whether or not they compress well. Otherwise
some simple heuristics are applied to detect an incompressible file. If the
first blocks written to a file are not compressible, the whole file is
permanently marked to skip compression.
the compression will allways be attempted, but the data may end up uncompressed
if the compression would make them larger.
+
Otherwise some simple heuristics are applied to detect an incompressible file.
If the first blocks written to a file are not compressible, the whole file is
permanently marked to skip compression. As this is too simple, the
'compress-force' is a workaround that will compress most of the files at the
cost of some wasted CPU cycles on failed attempts. The heuristics of 'compress'
will improve in the future so this will not be necessary.
+
NOTE: If compression is enabled, 'nodatacow' and 'nodatasum' are disabled.