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Diffstat (limited to 'Documentation/btrfs-filesystem.asciidoc')
| -rw-r--r-- | Documentation/btrfs-filesystem.asciidoc | 21 |
1 files changed, 13 insertions, 8 deletions
diff --git a/Documentation/btrfs-filesystem.asciidoc b/Documentation/btrfs-filesystem.asciidoc index 26c3fbc..31cd51b 100644 --- a/Documentation/btrfs-filesystem.asciidoc +++ b/Documentation/btrfs-filesystem.asciidoc @@ -49,27 +49,32 @@ Defragment file data and/or directory metadata *online*. If '-r' is passed, files in dir will be defragmented recursively. The start position and the number of bytes to defragment can be specified by start and len using '-s' and '-l' options below. -Any extent bigger than threshold given by '-t' option, will be considered -already defragged. -Use 0 to take the kernel default. +Extents bigger than value given by '-t' will be skipped, otherwise this value +is used as a target extent size, but is only advisory and may not be reached +if the free space is too fragmented. +Use 0 to take the kernel default, which is 256kB but may change in the future. You can also turn on compression in defragment operations. + `Options` + -v:::: be verbose --c:::: -compress file contents while defragmenting +-c[<algo>]:::: +compress file contents while defragmenting. Optional argument selects the compression +algorithm, 'zlib' (default) or 'lzo'. Currently it's not possible to select no +compression. -r:::: -defragment files recursively +defragment files recursively in given directories -f:::: -flush filesystem after defragmenting +flush data for each file before going to the next file. This will limit the amount +of dirty data to current file, otherwise the amount cumulates from several files +and may increase system load. -s <start>[kKmMgGtTpPeE]:::: defragment only from byte <start> onward -l <len>[kKmMgGtTpPeE]:::: defragment only up to <len> bytes -t <size>[kKmMgGtTpPeE]:::: -defragment only files at least <size> bytes big +target extent size, do not touch extents bigger than <size> + For <start>, <len>, <size> it is possible to append units designator: \'K', \'M', \'G', \'T', \'P', or \'E', which represent |