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xfs: only grab shared inode locks for source file during reflink 

Reflink and dedupe operations remap blocks from a source file into a
destination file.  The destination file needs exclusive locks on all
levels because we're updating its block map, but the source file isn't
undergoing any block map changes so we can use a shared lock.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Darrick J. Wong 2018-01-18 14:07:53 -08:00
parent 7c2d238ac6
commit 01c2e13dca
2 changed files with 20 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
fs/xfs/xfs_reflink.c
View File

@ -1202,13 +1202,16 @@ xfs_reflink_remap_blocks(
/* drange = (destoff, destoff + len); srange = (srcoff, srcoff + len) */
while (len) {
uint lock_mode;
trace_xfs_reflink_remap_blocks_loop(src, srcoff, len,
dest, destoff);
/* Read extent from the source file */
nimaps = 1;
xfs_ilock(src, XFS_ILOCK_EXCL);
lock_mode = xfs_ilock_data_map_shared(src);
error = xfs_bmapi_read(src, srcoff, len, &imap, &nimaps, 0);
xfs_iunlock(src, XFS_ILOCK_EXCL);
xfs_iunlock(src, lock_mode);
if (error)
goto err;
ASSERT(nimaps == 1);
@ -1260,7 +1263,7 @@ xfs_iolock_two_inodes_and_break_layout(
retry:
if (src < dest) {
inode_lock(src);
inode_lock_shared(src);
inode_lock_nested(dest, I_MUTEX_NONDIR2);
} else {
/* src >= dest */
@ -1271,7 +1274,7 @@ retry:
if (error == -EWOULDBLOCK) {
inode_unlock(dest);
if (src < dest)
inode_unlock(src);
inode_unlock_shared(src);
error = break_layout(dest, true);
if (error)
return error;
@ -1280,11 +1283,11 @@ retry:
if (error) {
inode_unlock(dest);
if (src < dest)
inode_unlock(src);
inode_unlock_shared(src);
return error;
}
if (src > dest)
inode_lock_nested(src, I_MUTEX_NONDIR2);
inode_lock_shared_nested(src, I_MUTEX_NONDIR2);
return 0;
}
@ -1324,7 +1327,7 @@ xfs_reflink_remap_range(
if (same_inode)
xfs_ilock(src, XFS_MMAPLOCK_EXCL);
else
xfs_lock_two_inodes(src, XFS_MMAPLOCK_EXCL, dest,
xfs_lock_two_inodes(src, XFS_MMAPLOCK_SHARED, dest,
XFS_MMAPLOCK_EXCL);
/* Check file eligibility and prepare for block sharing. */
@ -1393,10 +1396,12 @@ xfs_reflink_remap_range(
is_dedupe);
out_unlock:
xfs_iunlock(src, XFS_MMAPLOCK_EXCL);
xfs_iunlock(dest, XFS_MMAPLOCK_EXCL);
if (!same_inode)
xfs_iunlock(dest, XFS_MMAPLOCK_EXCL);
unlock_two_nondirectories(inode_in, inode_out);
xfs_iunlock(src, XFS_MMAPLOCK_SHARED);
inode_unlock(inode_out);
if (!same_inode)
inode_unlock_shared(inode_in);
if (ret)
trace_xfs_reflink_remap_range_error(dest, ret, _RET_IP_);
return ret;

5
include/linux/fs.h
View File

@ -748,6 +748,11 @@ static inline void inode_lock_nested(struct inode *inode, unsigned subclass)
down_write_nested(&inode->i_rwsem, subclass);
}
static inline void inode_lock_shared_nested(struct inode *inode, unsigned subclass)
{
down_read_nested(&inode->i_rwsem, subclass);
}
void lock_two_nondirectories(struct inode *, struct inode*);
void unlock_two_nondirectories(struct inode *, struct inode*);