174edb0e46
Due to the way the CoW algorithm in XFS works, there's an interval during which blocks allocated to handle a CoW can be lost -- if the FS goes down after the blocks are allocated but before the block remapping takes place. This is exacerbated by the cowextsz hint -- allocated reservations can sit around for a while, waiting to get used. Since the refcount btree doesn't normally store records with refcount of 1, we can use it to record these in-progress extents. In-progress blocks cannot be shared because they're not user-visible, so there shouldn't be any conflicts with other programs. This is a better solution than holding EFIs during writeback because (a) EFIs can't be relogged currently, (b) even if they could, EFIs are bound by available log space, which puts an unnecessary upper bound on how much CoW we can have in flight, and (c) we already have a mechanism to track blocks. At mount time, read the refcount records and free anything we find with a refcount of 1 because those were in-progress when the FS went down. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
48 lines
2.0 KiB
C
48 lines
2.0 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_range(struct xfs_inode *ip,
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xfs_off_t offset, xfs_off_t count);
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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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#endif /* __XFS_REFLINK_H */
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