xfs: more swap extent fixes for dynamic fork offsets
A new xfsqa test (226) with a prototype xfs_fsr change to try to handle dynamic fork offsets better triggers an assertion failure where the inode data fork is in btree format, yet there is room in the inode for it to be in extent format. The two inodes look like: before: ino 0x101 (target), num_extents 11, Max in-fork extents 6, broot size 40, fork offset 96 before: ino 0x115 (temp), num_extents 5, Max in-fork extents 3, broot size 40, fork offset 56 after: ino 0x101 (target), num_extents 5, Max in-fork extents 6, broot size 40, fork offset 96 after: ino 0x115 (temp), num_extents 11, Max in-fork extents 3, broot size 40, fork offset 56 Basically the target inode ends up with 5 extents in btree format, but it had space for 6 extents in extent format, so ends up incorrect. Notably here the broot size is the same, and that is where the kernel code is going wrong - the btree root will fit, so it lets the swap go ahead. The check should not allow the swap to take place if the number of extents while in btree format is less than the number of extents that can fit in the inode in extent format. Adding that check will prevent this swap and corruption from occurring. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
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