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https://github.com/kdave/btrfs-progs
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7781d1a2da
Currently, if user specifies value 'no' or 'none' on the command line,
it gets translated to an empty value that is passed to kernel. There was
a change in kernel 5.14 done by commit 5548c8c6f55b ("btrfs: props:
change how empty value is interpreted") that changes the behaviour
in that case.
The empty value is supposed to mean 'the default value' for any
property. For compression there is a need to distinguish resetting the
value and also setting the NOCOMPRESS property. The translation to empty
value makes that impossible.
The explanation and behaviour copied from the kernel patch:
Old behaviour:
$ lsattr file
---------------------- file
# the NOCOMPRESS bit is set
$ btrfs prop set file compression ''
$ lsattr file
---------------------m file
This is equivalent to 'btrfs prop set file compression no' in current
btrfs-progs as the 'no' or 'none' values are translated to an empty
string.
This is where the new behaviour is different: empty string drops the
compression flag (-c) and nocompress (-m):
$ lsattr file
---------------------- file
# No change
$ btrfs prop set file compression ''
$ lsattr file
---------------------- file
$ btrfs prop set file compression lzo
$ lsattr file
--------c------------- file
$ btrfs prop get file compression
compression=lzo
$ btrfs prop set file compression ''
# Reset to the initial state
$ lsattr file
---------------------- file
# Set NOCOMPRESS bit
$ btrfs prop set file compression no
$ lsattr file
---------------------m file
This obviously brings problems with backward compatibility, so this
patch should not be backported without making sure the updated
btrfs-progs are also used and that scripts have been updated to use the
new semantics.
Summary:
- old kernel:
no, none, "" - set NOCOMPRESS bit
- new kernel:
no, none - set NOCOMPRESS bit
"" - drop all compression flags, ie. COMPRESS and NOCOMPRESS
Signed-off-by: Li Zhang <zhanglikernel@gmail.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
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|---|---|---|
| .. | ||
| balance.c | ||
| commands.h | ||
| device.c | ||
| filesystem-du.c | ||
| filesystem-usage.c | ||
| filesystem-usage.h | ||
| filesystem.c | ||
| inspect-dump-super.c | ||
| inspect-dump-tree.c | ||
| inspect-tree-stats.c | ||
| inspect.c | ||
| property.c | ||
| props.h | ||
| qgroup.c | ||
| qgroup.h | ||
| quota.c | ||
| receive-dump.c | ||
| receive-dump.h | ||
| receive.c | ||
| replace.c | ||
| rescue-chunk-recover.c | ||
| rescue-super-recover.c | ||
| rescue.c | ||
| rescue.h | ||
| restore.c | ||
| scrub.c | ||
| send.c | ||
| subvolume-list.c | ||
| subvolume.c | ||