Commit 01c2e13d authored by Darrick J. Wong's avatar Darrick J. Wong
Browse files

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: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
parent 7c2d238a

fs/xfs/xfs_reflink.c

+15 −10
Original line number Diff line number Diff line
@@ -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);

	if (!same_inode)

	xfs_iunlock(dest, XFS_MMAPLOCK_EXCL);

	unlock_two_nondirectories(inode_in, inode_out);

	if (!same_inode)

		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;

include/linux/fs.h

+5 −0
Original line number Diff line number Diff line
@@ -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*);

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