xfs: rewrite getbmap using the xfs_iext_* helpers
Currently getbmap uses xfs_bmapi_read to query the extent map, and then
fixes up various bits that are eventually reported to userspace.
This patch instead rewrites it to use xfs_iext_lookup_extent and
xfs_iext_get_extent to iteratively process the extent map. This not
only avoids the need to allocate a map for the returned xfs_bmbt_irec
structures but also greatly simplified the code.
There are two intentional behavior changes compared to the old code:
- the current code reports unwritten extents that don't directly border
a written one as unwritten even when not passing the BMV_IF_PREALLOC
option, contrary to the documentation. The new code requires the
BMV_IF_PREALLOC flag to report the unwrittent extent bit.
- The new code does never merges consecutive extents, unlike the old
code that sometimes does it based on the boundaries of the
xfs_bmapi_read calls. Note that the extent merging behavior was
entirely undocumented.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
1 file changed