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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>
74 lines
2.5 KiB
C
74 lines
2.5 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_REFCOUNT_BTREE_H__
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#define __XFS_REFCOUNT_BTREE_H__
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/*
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* Reference Count Btree on-disk structures
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*/
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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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/*
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* Btree block header size
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*/
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#define XFS_REFCOUNT_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_REFCOUNT_REC_ADDR(block, index) \
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((struct xfs_refcount_rec *) \
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((char *)(block) + \
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XFS_REFCOUNT_BLOCK_LEN + \
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(((index) - 1) * sizeof(struct xfs_refcount_rec))))
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#define XFS_REFCOUNT_KEY_ADDR(block, index) \
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((struct xfs_refcount_key *) \
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((char *)(block) + \
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XFS_REFCOUNT_BLOCK_LEN + \
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((index) - 1) * sizeof(struct xfs_refcount_key)))
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#define XFS_REFCOUNT_PTR_ADDR(block, index, maxrecs) \
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((xfs_refcount_ptr_t *) \
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((char *)(block) + \
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XFS_REFCOUNT_BLOCK_LEN + \
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(maxrecs) * sizeof(struct xfs_refcount_key) + \
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((index) - 1) * sizeof(xfs_refcount_ptr_t)))
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extern struct xfs_btree_cur *xfs_refcountbt_init_cursor(struct xfs_mount *mp,
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struct xfs_trans *tp, struct xfs_buf *agbp, xfs_agnumber_t agno,
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struct xfs_defer_ops *dfops);
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extern int xfs_refcountbt_maxrecs(struct xfs_mount *mp, int blocklen,
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bool leaf);
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extern void xfs_refcountbt_compute_maxlevels(struct xfs_mount *mp);
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extern xfs_extlen_t xfs_refcountbt_calc_size(struct xfs_mount *mp,
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unsigned long long len);
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extern xfs_extlen_t xfs_refcountbt_max_size(struct xfs_mount *mp);
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extern int xfs_refcountbt_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_REFCOUNT_BTREE_H__ */
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