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Josef Bacik authored
We have been iterating all references for each extent we have in a file when we do fiemap to see if it is shared. This is fine when you have a few clones or a few snapshots, but when you have 5k snapshots suddenly fiemap just sits there and stares at you. So add btrfs_check_shared which will use the backref walking code but will short circuit as soon as it finds a root or inode that doesn't match the one we currently have. This makes fiemap on my testbox go from looking at me blankly for a day to spitting out actual output in a reasonable amount of time. Thanks, Signed-off-by:
Josef Bacik <jbacik@fb.com> Signed-off-by:
Chris Mason <clm@fb.com>
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