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The cowblocks background scanner currently clears the cowblocks tag for inodes without any real allocations in the cow fork. This excludes inodes with only delalloc blocks in the cow fork. While we might never expect to clear delalloc blocks from the cow fork in the background scanner, it is not necessarily correct to clear the cowblocks tag from such inodes. For example, if the background scanner happens to process an inode between a buffered write and writeback, the scanner catches the inode in a state after delalloc blocks have been allocated to the cow fork but before the delalloc blocks have been converted to real blocks by writeback. The background scanner then incorrectly clears the cowblocks tag, even if part of the aforementioned delalloc reservation will not be remapped to the data fork (i.e., extra blocks due to the cowextsize hint). This means that any such additional blocks in the cow fork might never be reclaimed by the background scanner and could persist until the inode itself is reclaimed. To address this problem, only skip and clear inodes without any cow fork allocations whatsoever from the background scanner. While we generally do not want to cancel delalloc reservations from the background scanner, the pagecache dirty check following the cowblocks check should prevent that situation. If we do end up with delalloc cow fork blocks without a dirty address space mapping, this is probably an indication that something has gone wrong and the blocks should be reclaimed, as they may never be converted to a real allocation. Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
54 lines
2.3 KiB
C
54 lines
2.3 KiB
C
/*
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* Copyright (C) 2016 Oracle. All Rights Reserved.
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*
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* Author: Darrick J. Wong <darrick.wong@oracle.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it would be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#ifndef __XFS_REFLINK_H
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#define __XFS_REFLINK_H 1
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extern int xfs_reflink_find_shared(struct xfs_mount *mp, xfs_agnumber_t agno,
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xfs_agblock_t agbno, xfs_extlen_t aglen, xfs_agblock_t *fbno,
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xfs_extlen_t *flen, bool find_maximal);
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extern int xfs_reflink_trim_around_shared(struct xfs_inode *ip,
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struct xfs_bmbt_irec *irec, bool *shared, bool *trimmed);
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extern int xfs_reflink_reserve_cow(struct xfs_inode *ip,
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struct xfs_bmbt_irec *imap, bool *shared);
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extern int xfs_reflink_allocate_cow_range(struct xfs_inode *ip,
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xfs_off_t offset, xfs_off_t count);
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extern bool xfs_reflink_find_cow_mapping(struct xfs_inode *ip, xfs_off_t offset,
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struct xfs_bmbt_irec *imap, bool *need_alloc);
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extern int xfs_reflink_trim_irec_to_next_cow(struct xfs_inode *ip,
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xfs_fileoff_t offset_fsb, struct xfs_bmbt_irec *imap);
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extern int xfs_reflink_cancel_cow_blocks(struct xfs_inode *ip,
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struct xfs_trans **tpp, xfs_fileoff_t offset_fsb,
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xfs_fileoff_t end_fsb);
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extern int xfs_reflink_cancel_cow_range(struct xfs_inode *ip, xfs_off_t offset,
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xfs_off_t count);
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extern int xfs_reflink_end_cow(struct xfs_inode *ip, xfs_off_t offset,
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xfs_off_t count);
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extern int xfs_reflink_recover_cow(struct xfs_mount *mp);
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extern int xfs_reflink_remap_range(struct file *file_in, loff_t pos_in,
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struct file *file_out, loff_t pos_out, u64 len, bool is_dedupe);
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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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