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diff --git a/Documentation/btrfs-check.asciidoc b/Documentation/btrfs-check.asciidoc new file mode 100644 index 00000000..74a2ad21 --- /dev/null +++ b/Documentation/btrfs-check.asciidoc @@ -0,0 +1,111 @@ +btrfs-check(8) +============== + +NAME +---- +btrfs-check - check or repair an unmounted btrfs filesystem + +SYNOPSIS +-------- +*btrfs check* [options] <device> + +DESCRIPTION +----------- + +The filesystem checker is used to verify structural integrity of a filesystem +and attempt to repair it if requested. The filesystem must be unmounted. + +By default, *btrfs check* will not modify the device but you can reaffirm that +by the option '--readonly'. + +*btrfsck* is an alias of *btrfs check* command and is now deprecated. + +WARNING: Do not use '--repair' unless you are adviced to by a developer, an +experienced user or accept the fact that 'fsck' cannot possibly fix all sorts +of damage that could happen to a filesystem because of software and hardware +bugs. + +The structural integrity check verifies if internal filesystem objects or +data structures satisfy the constraints, point to the right objects or are +correctly connected together. + +There are several cross checks that can detect wrong reference counts of shared +extents, backrefrences, missing extents of inodes, directory and inode +connectivity etc. + +The amount of memory required can be high, depending on the size of the +filesystem, smililarly the run time. + +SAFE OR ADVISORY OPTIONS +------------------------ + +-b|--backup:: +use the first valid set of backup roots stored in the superblock ++ +This can be combined with '--super' if some of the superblocks are damaged. + +--check-data-csum:: +verify checksums of data blocks ++ +This expects that the filesystem is otherwise +OK, so this is basically and offline 'scrub' but does not repair data from +spare coipes. + +--chunk-root <bytenr>:: +use the given offset 'bytenr' for the chunk tree root + +-E|--subvol-extents <subvolid>:: +show extent state for the given subvolume + +-p|--progress:: +indicate progress at various checking phases + +--qgroup-report:: +verify qgroup accounting and compare against filesystem accounting + +-r|--tree-root <bytenr>:: +use the given offset 'bytenr' for the tree root + +--readonly:: +(default) +run in read-only mode, this option exists to calm potential panic when users +are going to run the checker + +-s|--super <superblock>:: +use 'superblock'th superblock copy, valid values are 0, 1 or 2 if the +respective superblock offset is within the device size ++ +This can be used to use a different starting point if some of the primary +superblock is damaged. + +DANGEROUS OPTIONS +----------------- + +--repair:: +enable the repair mode and attempt to fix problems where possible +--init-csum-tree:: +create a new checksum tree and recalculate checksums in all files ++ +NOTE: Do not blindly use this option to fix checksum mismatch problems. + +--init-extent-tree:: +build the extent tree from scratch ++ +NOTE: Do not use unless you know what you're doing. + +EXIT STATUS +----------- +*btrfs check* returns a zero exit status if it succeeds. Non zero is +returned in case of failure. + +AVAILABILITY +------------ +*btrfs* is part of btrfs-progs. +Please refer to the btrfs wiki http://btrfs.wiki.kernel.org for +further details. + +SEE ALSO +-------- +`mkfs.btrfs`(8), +`btrfs-scrub`(8), +`btrfs-rescue`(8) |