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84d6961910
To gracefully handle the situation where a CoW operation turns a single refcount extent into a lot of tiny ones and then run out of space when a tree split has to happen, use the per-AG reserved block pool to pre-allocate all the space we'll ever need for a maximal btree. For a 4K block size, this only costs an overhead of 0.3% of available disk space. When reflink is enabled, we have an unfortunate problem with rmap -- since we can share a block billions of times, this means that the reverse mapping btree can expand basically infinitely. When an AG is so full that there are no free blocks with which to expand the rmapbt, the filesystem will shut down hard. This is rather annoying to the user, so use the AG reservation code to reserve a "reasonable" amount of space for rmap. We'll prevent reflinks and CoW operations if we think we're getting close to exhausting an AG's free space rather than shutting down, but this permanent reservation should be enough for "most" users. Hopefully. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> [hch@lst.de: ensure that we invalidate the freed btree buffer] Signed-off-by: Christoph Hellwig <hch@lst.de>
68 lines
2.4 KiB
C
68 lines
2.4 KiB
C
/*
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* Copyright (c) 2014 Red Hat, Inc.
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* All Rights Reserved.
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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 as
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* published by the Free Software Foundation.
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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_RMAP_BTREE_H__
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#define __XFS_RMAP_BTREE_H__
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struct xfs_buf;
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struct xfs_btree_cur;
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struct xfs_mount;
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/* rmaps only exist on crc enabled filesystems */
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#define XFS_RMAP_BLOCK_LEN XFS_BTREE_SBLOCK_CRC_LEN
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/*
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* Record, key, and pointer address macros for btree blocks.
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*
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* (note that some of these may appear unused, but they are used in userspace)
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*/
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#define XFS_RMAP_REC_ADDR(block, index) \
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((struct xfs_rmap_rec *) \
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((char *)(block) + XFS_RMAP_BLOCK_LEN + \
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(((index) - 1) * sizeof(struct xfs_rmap_rec))))
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#define XFS_RMAP_KEY_ADDR(block, index) \
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((struct xfs_rmap_key *) \
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((char *)(block) + XFS_RMAP_BLOCK_LEN + \
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((index) - 1) * 2 * sizeof(struct xfs_rmap_key)))
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#define XFS_RMAP_HIGH_KEY_ADDR(block, index) \
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((struct xfs_rmap_key *) \
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((char *)(block) + XFS_RMAP_BLOCK_LEN + \
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sizeof(struct xfs_rmap_key) + \
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((index) - 1) * 2 * sizeof(struct xfs_rmap_key)))
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#define XFS_RMAP_PTR_ADDR(block, index, maxrecs) \
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((xfs_rmap_ptr_t *) \
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((char *)(block) + XFS_RMAP_BLOCK_LEN + \
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(maxrecs) * 2 * sizeof(struct xfs_rmap_key) + \
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((index) - 1) * sizeof(xfs_rmap_ptr_t)))
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struct xfs_btree_cur *xfs_rmapbt_init_cursor(struct xfs_mount *mp,
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struct xfs_trans *tp, struct xfs_buf *bp,
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xfs_agnumber_t agno);
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int xfs_rmapbt_maxrecs(struct xfs_mount *mp, int blocklen, int leaf);
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extern void xfs_rmapbt_compute_maxlevels(struct xfs_mount *mp);
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extern xfs_extlen_t xfs_rmapbt_calc_size(struct xfs_mount *mp,
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unsigned long long len);
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extern xfs_extlen_t xfs_rmapbt_max_size(struct xfs_mount *mp);
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extern int xfs_rmapbt_calc_reserves(struct xfs_mount *mp,
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xfs_agnumber_t agno, xfs_extlen_t *ask, xfs_extlen_t *used);
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#endif /* __XFS_RMAP_BTREE_H__ */
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