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Commit 98cc2db5 authored by Darrick J. Wong's avatar Darrick J. Wong
Browse files

xfs: unshare a range of blocks via fallocate 



Unshare all shared extents if the user calls fallocate with the new
unshare mode flag set, so that we can guarantee that a subsequent
write will not ENOSPC.

Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
[hch: pass inode instead of file to xfs_reflink_dirty_range,
      use iomap infrastructure for copy up]
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent f0bc4d13

fs/xfs/xfs_file.c

+8 −2
Original line number Diff line number Diff line
@@ -848,7 +848,7 @@ xfs_file_write_iter( 
#define	XFS_FALLOC_FL_SUPPORTED						\

		(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |		\

		 FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE |	\

		 FALLOC_FL_INSERT_RANGE)

		 FALLOC_FL_INSERT_RANGE | FALLOC_FL_UNSHARE_RANGE)



STATIC long

xfs_file_fallocate(
@@ -938,9 +938,15 @@ xfs_file_fallocate( 


		if (mode & FALLOC_FL_ZERO_RANGE)

			error = xfs_zero_file_space(ip, offset, len);

		else

		else {

			if (mode & FALLOC_FL_UNSHARE_RANGE) {

				error = xfs_reflink_unshare(ip, offset, len);

				if (error)

					goto out_unlock;

			}

			error = xfs_alloc_file_space(ip, offset, len,

						     XFS_BMAPI_PREALLOC);

		}

		if (error)

			goto out_unlock;

	}

fs/xfs/xfs_reflink.c

+255 −0
Original line number Diff line number Diff line
@@ -1345,3 +1345,258 @@ xfs_reflink_remap_range( 
		trace_xfs_reflink_remap_range_error(dest, error, _RET_IP_);

	return error;

}



/*

 * The user wants to preemptively CoW all shared blocks in this file,

 * which enables us to turn off the reflink flag.  Iterate all

 * extents which are not prealloc/delalloc to see which ranges are

 * mentioned in the refcount tree, then read those blocks into the

 * pagecache, dirty them, fsync them back out, and then we can update

 * the inode flag.  What happens if we run out of memory? :)

 */

STATIC int

xfs_reflink_dirty_extents(

	struct xfs_inode	*ip,

	xfs_fileoff_t		fbno,

	xfs_filblks_t		end,

	xfs_off_t		isize)

{

	struct xfs_mount	*mp = ip->i_mount;

	xfs_agnumber_t		agno;

	xfs_agblock_t		agbno;

	xfs_extlen_t		aglen;

	xfs_agblock_t		rbno;

	xfs_extlen_t		rlen;

	xfs_off_t		fpos;

	xfs_off_t		flen;

	struct xfs_bmbt_irec	map[2];

	int			nmaps;

	int			error;



	while (end - fbno > 0) {

		nmaps = 1;

		/*

		 * Look for extents in the file.  Skip holes, delalloc, or

		 * unwritten extents; they can't be reflinked.

		 */

		error = xfs_bmapi_read(ip, fbno, end - fbno, map, &nmaps, 0);

		if (error)

			goto out;

		if (nmaps == 0)

			break;

		if (map[0].br_startblock == HOLESTARTBLOCK ||

		    map[0].br_startblock == DELAYSTARTBLOCK ||

		    ISUNWRITTEN(&map[0]))

			goto next;



		map[1] = map[0];

		while (map[1].br_blockcount) {

			agno = XFS_FSB_TO_AGNO(mp, map[1].br_startblock);

			agbno = XFS_FSB_TO_AGBNO(mp, map[1].br_startblock);

			aglen = map[1].br_blockcount;



			error = xfs_reflink_find_shared(mp, agno, agbno, aglen,

					&rbno, &rlen, true);

			if (error)

				goto out;

			if (rbno == NULLAGBLOCK)

				break;



			/* Dirty the pages */

			xfs_iunlock(ip, XFS_ILOCK_EXCL);

			fpos = XFS_FSB_TO_B(mp, map[1].br_startoff +

					(rbno - agbno));

			flen = XFS_FSB_TO_B(mp, rlen);

			if (fpos + flen > isize)

				flen = isize - fpos;

			error = iomap_file_dirty(VFS_I(ip), fpos, flen,

					&xfs_iomap_ops);

			xfs_ilock(ip, XFS_ILOCK_EXCL);

			if (error)

				goto out;



			map[1].br_blockcount -= (rbno - agbno + rlen);

			map[1].br_startoff += (rbno - agbno + rlen);

			map[1].br_startblock += (rbno - agbno + rlen);

		}



next:

		fbno = map[0].br_startoff + map[0].br_blockcount;

	}

out:

	return error;

}



/* Clear the inode reflink flag if there are no shared extents. */

int

xfs_reflink_clear_inode_flag(

	struct xfs_inode	*ip,

	struct xfs_trans	**tpp)

{

	struct xfs_mount	*mp = ip->i_mount;

	xfs_fileoff_t		fbno;

	xfs_filblks_t		end;

	xfs_agnumber_t		agno;

	xfs_agblock_t		agbno;

	xfs_extlen_t		aglen;

	xfs_agblock_t		rbno;

	xfs_extlen_t		rlen;

	struct xfs_bmbt_irec	map[2];

	int			nmaps;

	int			error = 0;



	if (!(ip->i_d.di_flags2 & XFS_DIFLAG2_REFLINK))

		return 0;



	fbno = 0;

	end = XFS_B_TO_FSB(mp, i_size_read(VFS_I(ip)));

	while (end - fbno > 0) {

		nmaps = 1;

		/*

		 * Look for extents in the file.  Skip holes, delalloc, or

		 * unwritten extents; they can't be reflinked.

		 */

		error = xfs_bmapi_read(ip, fbno, end - fbno, map, &nmaps, 0);

		if (error)

			return error;

		if (nmaps == 0)

			break;

		if (map[0].br_startblock == HOLESTARTBLOCK ||

		    map[0].br_startblock == DELAYSTARTBLOCK ||

		    ISUNWRITTEN(&map[0]))

			goto next;



		map[1] = map[0];

		while (map[1].br_blockcount) {

			agno = XFS_FSB_TO_AGNO(mp, map[1].br_startblock);

			agbno = XFS_FSB_TO_AGBNO(mp, map[1].br_startblock);

			aglen = map[1].br_blockcount;



			error = xfs_reflink_find_shared(mp, agno, agbno, aglen,

					&rbno, &rlen, false);

			if (error)

				return error;

			/* Is there still a shared block here? */

			if (rbno != NULLAGBLOCK)

				return 0;



			map[1].br_blockcount -= aglen;

			map[1].br_startoff += aglen;

			map[1].br_startblock += aglen;

		}



next:

		fbno = map[0].br_startoff + map[0].br_blockcount;

	}



	/*

	 * We didn't find any shared blocks so turn off the reflink flag.

	 * First, get rid of any leftover CoW mappings.

	 */

	error = xfs_reflink_cancel_cow_blocks(ip, tpp, 0, NULLFILEOFF);

	if (error)

		return error;



	/* Clear the inode flag. */

	trace_xfs_reflink_unset_inode_flag(ip);

	ip->i_d.di_flags2 &= ~XFS_DIFLAG2_REFLINK;

	xfs_trans_ijoin(*tpp, ip, 0);

	xfs_trans_log_inode(*tpp, ip, XFS_ILOG_CORE);



	return error;

}



/*

 * Clear the inode reflink flag if there are no shared extents and the size

 * hasn't changed.

 */

STATIC int

xfs_reflink_try_clear_inode_flag(

	struct xfs_inode	*ip,

	xfs_off_t		old_isize)

{

	struct xfs_mount	*mp = ip->i_mount;

	struct xfs_trans	*tp;

	int			error = 0;



	/* Start a rolling transaction to remove the mappings */

	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0, 0, &tp);

	if (error)

		return error;



	xfs_ilock(ip, XFS_ILOCK_EXCL);

	xfs_trans_ijoin(tp, ip, 0);



	if (old_isize != i_size_read(VFS_I(ip)))

		goto cancel;



	error = xfs_reflink_clear_inode_flag(ip, &tp);

	if (error)

		goto cancel;



	error = xfs_trans_commit(tp);

	if (error)

		goto out;



	xfs_iunlock(ip, XFS_ILOCK_EXCL);

	return 0;

cancel:

	xfs_trans_cancel(tp);

out:

	xfs_iunlock(ip, XFS_ILOCK_EXCL);

	return error;

}



/*

 * Pre-COW all shared blocks within a given byte range of a file and turn off

 * the reflink flag if we unshare all of the file's blocks.

 */

int

xfs_reflink_unshare(

	struct xfs_inode	*ip,

	xfs_off_t		offset,

	xfs_off_t		len)

{

	struct xfs_mount	*mp = ip->i_mount;

	xfs_fileoff_t		fbno;

	xfs_filblks_t		end;

	xfs_off_t		isize;

	int			error;



	if (!xfs_is_reflink_inode(ip))

		return 0;



	trace_xfs_reflink_unshare(ip, offset, len);



	inode_dio_wait(VFS_I(ip));



	/* Try to CoW the selected ranges */

	xfs_ilock(ip, XFS_ILOCK_EXCL);

	fbno = XFS_B_TO_FSB(mp, offset);

	isize = i_size_read(VFS_I(ip));

	end = XFS_B_TO_FSB(mp, offset + len);

	error = xfs_reflink_dirty_extents(ip, fbno, end, isize);

	if (error)

		goto out_unlock;

	xfs_iunlock(ip, XFS_ILOCK_EXCL);



	/* Wait for the IO to finish */

	error = filemap_write_and_wait(VFS_I(ip)->i_mapping);

	if (error)

		goto out;



	/* Turn off the reflink flag if we unshared the whole file */

	if (offset == 0 && len == isize) {

		error = xfs_reflink_try_clear_inode_flag(ip, isize);

		if (error)

			goto out;

	}



	return 0;



out_unlock:

	xfs_iunlock(ip, XFS_ILOCK_EXCL);

out:

	trace_xfs_reflink_unshare_error(ip, error, _RET_IP_);

	return error;

}

fs/xfs/xfs_reflink.h

+4 −0
Original line number Diff line number Diff line
@@ -48,5 +48,9 @@ extern int xfs_reflink_recover_cow(struct xfs_mount *mp); 
extern int xfs_reflink_remap_range(struct xfs_inode *src, xfs_off_t srcoff,

		struct xfs_inode *dest, xfs_off_t destoff, xfs_off_t len,

		unsigned int flags);

extern int xfs_reflink_clear_inode_flag(struct xfs_inode *ip,

		struct xfs_trans **tpp);

extern int xfs_reflink_unshare(struct xfs_inode *ip, xfs_off_t offset,

		xfs_off_t len);



#endif /* __XFS_REFLINK_H */