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: Darrick 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: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Darrick J. Wong
parent
f0bc4d134b
commit
98cc2db5b8
@ -848,7 +848,7 @@ buffered:
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#define XFS_FALLOC_FL_SUPPORTED \
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(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE | \
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FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE | \
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FALLOC_FL_INSERT_RANGE)
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FALLOC_FL_INSERT_RANGE | FALLOC_FL_UNSHARE_RANGE)
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STATIC long
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xfs_file_fallocate(
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@ -938,9 +938,15 @@ xfs_file_fallocate(
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if (mode & FALLOC_FL_ZERO_RANGE)
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error = xfs_zero_file_space(ip, offset, len);
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else
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else {
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if (mode & FALLOC_FL_UNSHARE_RANGE) {
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error = xfs_reflink_unshare(ip, offset, len);
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if (error)
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goto out_unlock;
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}
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error = xfs_alloc_file_space(ip, offset, len,
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XFS_BMAPI_PREALLOC);
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}
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if (error)
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goto out_unlock;
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}
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@ -1345,3 +1345,258 @@ out_error:
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trace_xfs_reflink_remap_range_error(dest, error, _RET_IP_);
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return error;
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}
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/*
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* The user wants to preemptively CoW all shared blocks in this file,
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* which enables us to turn off the reflink flag. Iterate all
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* extents which are not prealloc/delalloc to see which ranges are
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* mentioned in the refcount tree, then read those blocks into the
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* pagecache, dirty them, fsync them back out, and then we can update
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* the inode flag. What happens if we run out of memory? :)
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*/
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STATIC int
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xfs_reflink_dirty_extents(
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struct xfs_inode *ip,
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xfs_fileoff_t fbno,
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xfs_filblks_t end,
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xfs_off_t isize)
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{
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struct xfs_mount *mp = ip->i_mount;
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xfs_agnumber_t agno;
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xfs_agblock_t agbno;
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xfs_extlen_t aglen;
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xfs_agblock_t rbno;
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xfs_extlen_t rlen;
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xfs_off_t fpos;
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xfs_off_t flen;
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struct xfs_bmbt_irec map[2];
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int nmaps;
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int error;
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while (end - fbno > 0) {
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nmaps = 1;
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/*
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* Look for extents in the file. Skip holes, delalloc, or
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* unwritten extents; they can't be reflinked.
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*/
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error = xfs_bmapi_read(ip, fbno, end - fbno, map, &nmaps, 0);
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if (error)
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goto out;
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if (nmaps == 0)
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break;
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if (map[0].br_startblock == HOLESTARTBLOCK ||
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map[0].br_startblock == DELAYSTARTBLOCK ||
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ISUNWRITTEN(&map[0]))
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goto next;
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map[1] = map[0];
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while (map[1].br_blockcount) {
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agno = XFS_FSB_TO_AGNO(mp, map[1].br_startblock);
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agbno = XFS_FSB_TO_AGBNO(mp, map[1].br_startblock);
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aglen = map[1].br_blockcount;
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error = xfs_reflink_find_shared(mp, agno, agbno, aglen,
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&rbno, &rlen, true);
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if (error)
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goto out;
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if (rbno == NULLAGBLOCK)
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break;
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/* Dirty the pages */
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xfs_iunlock(ip, XFS_ILOCK_EXCL);
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fpos = XFS_FSB_TO_B(mp, map[1].br_startoff +
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(rbno - agbno));
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flen = XFS_FSB_TO_B(mp, rlen);
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if (fpos + flen > isize)
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flen = isize - fpos;
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error = iomap_file_dirty(VFS_I(ip), fpos, flen,
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&xfs_iomap_ops);
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xfs_ilock(ip, XFS_ILOCK_EXCL);
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if (error)
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goto out;
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map[1].br_blockcount -= (rbno - agbno + rlen);
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map[1].br_startoff += (rbno - agbno + rlen);
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map[1].br_startblock += (rbno - agbno + rlen);
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}
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next:
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fbno = map[0].br_startoff + map[0].br_blockcount;
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}
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out:
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return error;
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}
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/* Clear the inode reflink flag if there are no shared extents. */
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int
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xfs_reflink_clear_inode_flag(
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struct xfs_inode *ip,
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struct xfs_trans **tpp)
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{
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struct xfs_mount *mp = ip->i_mount;
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xfs_fileoff_t fbno;
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xfs_filblks_t end;
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xfs_agnumber_t agno;
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xfs_agblock_t agbno;
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xfs_extlen_t aglen;
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xfs_agblock_t rbno;
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xfs_extlen_t rlen;
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struct xfs_bmbt_irec map[2];
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int nmaps;
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int error = 0;
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if (!(ip->i_d.di_flags2 & XFS_DIFLAG2_REFLINK))
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return 0;
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fbno = 0;
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end = XFS_B_TO_FSB(mp, i_size_read(VFS_I(ip)));
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while (end - fbno > 0) {
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nmaps = 1;
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/*
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* Look for extents in the file. Skip holes, delalloc, or
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* unwritten extents; they can't be reflinked.
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*/
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error = xfs_bmapi_read(ip, fbno, end - fbno, map, &nmaps, 0);
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if (error)
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return error;
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if (nmaps == 0)
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break;
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if (map[0].br_startblock == HOLESTARTBLOCK ||
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map[0].br_startblock == DELAYSTARTBLOCK ||
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ISUNWRITTEN(&map[0]))
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goto next;
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map[1] = map[0];
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while (map[1].br_blockcount) {
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agno = XFS_FSB_TO_AGNO(mp, map[1].br_startblock);
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agbno = XFS_FSB_TO_AGBNO(mp, map[1].br_startblock);
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aglen = map[1].br_blockcount;
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error = xfs_reflink_find_shared(mp, agno, agbno, aglen,
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&rbno, &rlen, false);
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if (error)
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return error;
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/* Is there still a shared block here? */
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if (rbno != NULLAGBLOCK)
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return 0;
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map[1].br_blockcount -= aglen;
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map[1].br_startoff += aglen;
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map[1].br_startblock += aglen;
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}
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next:
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fbno = map[0].br_startoff + map[0].br_blockcount;
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}
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/*
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* We didn't find any shared blocks so turn off the reflink flag.
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* First, get rid of any leftover CoW mappings.
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*/
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error = xfs_reflink_cancel_cow_blocks(ip, tpp, 0, NULLFILEOFF);
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if (error)
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return error;
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/* Clear the inode flag. */
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trace_xfs_reflink_unset_inode_flag(ip);
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ip->i_d.di_flags2 &= ~XFS_DIFLAG2_REFLINK;
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xfs_trans_ijoin(*tpp, ip, 0);
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xfs_trans_log_inode(*tpp, ip, XFS_ILOG_CORE);
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return error;
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}
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/*
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* Clear the inode reflink flag if there are no shared extents and the size
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* hasn't changed.
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*/
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STATIC int
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xfs_reflink_try_clear_inode_flag(
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struct xfs_inode *ip,
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xfs_off_t old_isize)
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{
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struct xfs_mount *mp = ip->i_mount;
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struct xfs_trans *tp;
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int error = 0;
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/* Start a rolling transaction to remove the mappings */
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error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, 0, 0, 0, &tp);
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if (error)
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return error;
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xfs_ilock(ip, XFS_ILOCK_EXCL);
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xfs_trans_ijoin(tp, ip, 0);
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if (old_isize != i_size_read(VFS_I(ip)))
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goto cancel;
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error = xfs_reflink_clear_inode_flag(ip, &tp);
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if (error)
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goto cancel;
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error = xfs_trans_commit(tp);
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if (error)
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goto out;
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xfs_iunlock(ip, XFS_ILOCK_EXCL);
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return 0;
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cancel:
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xfs_trans_cancel(tp);
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out:
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xfs_iunlock(ip, XFS_ILOCK_EXCL);
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return error;
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}
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/*
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* Pre-COW all shared blocks within a given byte range of a file and turn off
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* the reflink flag if we unshare all of the file's blocks.
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*/
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int
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xfs_reflink_unshare(
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struct xfs_inode *ip,
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xfs_off_t offset,
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xfs_off_t len)
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{
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struct xfs_mount *mp = ip->i_mount;
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xfs_fileoff_t fbno;
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xfs_filblks_t end;
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xfs_off_t isize;
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int error;
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if (!xfs_is_reflink_inode(ip))
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return 0;
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trace_xfs_reflink_unshare(ip, offset, len);
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inode_dio_wait(VFS_I(ip));
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/* Try to CoW the selected ranges */
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xfs_ilock(ip, XFS_ILOCK_EXCL);
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fbno = XFS_B_TO_FSB(mp, offset);
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isize = i_size_read(VFS_I(ip));
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end = XFS_B_TO_FSB(mp, offset + len);
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error = xfs_reflink_dirty_extents(ip, fbno, end, isize);
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if (error)
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goto out_unlock;
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xfs_iunlock(ip, XFS_ILOCK_EXCL);
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/* Wait for the IO to finish */
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error = filemap_write_and_wait(VFS_I(ip)->i_mapping);
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if (error)
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goto out;
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/* Turn off the reflink flag if we unshared the whole file */
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if (offset == 0 && len == isize) {
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error = xfs_reflink_try_clear_inode_flag(ip, isize);
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if (error)
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goto out;
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}
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return 0;
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out_unlock:
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xfs_iunlock(ip, XFS_ILOCK_EXCL);
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out:
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trace_xfs_reflink_unshare_error(ip, error, _RET_IP_);
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return error;
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}
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@ -48,5 +48,9 @@ extern int xfs_reflink_recover_cow(struct xfs_mount *mp);
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extern int xfs_reflink_remap_range(struct xfs_inode *src, xfs_off_t srcoff,
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struct xfs_inode *dest, xfs_off_t destoff, xfs_off_t len,
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unsigned int flags);
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extern int xfs_reflink_clear_inode_flag(struct xfs_inode *ip,
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struct xfs_trans **tpp);
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extern int xfs_reflink_unshare(struct xfs_inode *ip, xfs_off_t offset,
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xfs_off_t len);
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#endif /* __XFS_REFLINK_H */
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