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authorDarrick J. Wong <darrick.wong@oracle.com>2016-10-03 09:11:36 -0700
committerDarrick J. Wong <darrick.wong@oracle.com>2016-10-05 16:26:04 -0700
commitdb1327b16c2b24e28d1e5899bced89db9ae6538e (patch)
tree26387f590ce880b409245a80c40dabe47a7dc6e5 /fs/xfs/xfs_aops.c
parent43caeb187deb92b3cc343fce9c2310512f6ac9cd (diff)
downloadlinux-db1327b16c2b24e28d1e5899bced89db9ae6538e.tar.bz2
xfs: report shared extent mappings to userspace correctly
Report shared extents through the iomap interface so that FIEMAP flags shared blocks accurately. Have xfs_vm_bmap return zero for reflinked files because the bmap-based swap code requires static block mappings, which is incompatible with copy on write. NOTE: Existing userspace bmap users such as lilo will have the same problem with reflink files. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Diffstat (limited to 'fs/xfs/xfs_aops.c')
-rw-r--r--fs/xfs/xfs_aops.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index f6f5bbc39dda..2f4a15ec9ee9 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -1508,6 +1508,17 @@ xfs_vm_bmap(
trace_xfs_vm_bmap(XFS_I(inode));
xfs_ilock(ip, XFS_IOLOCK_SHARED);
+
+ /*
+ * The swap code (ab-)uses ->bmap to get a block mapping and then
+ * bypasseѕ the file system for actual I/O. We really can't allow
+ * that on reflinks inodes, so we have to skip out here. And yes,
+ * 0 is the magic code for a bmap error..
+ */
+ if (xfs_is_reflink_inode(ip)) {
+ xfs_iunlock(ip, XFS_IOLOCK_SHARED);
+ return 0;
+ }
filemap_write_and_wait(mapping);
xfs_iunlock(ip, XFS_IOLOCK_SHARED);
return generic_block_bmap(mapping, block, xfs_get_blocks);