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xfs: reserve enough blocks to handle btree splits when remapping

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In xfs_reflink_end_cow, we erroneously reserve only enough blocks to
handle adding 1 extent.  This is problematic if we fragment free space,
have to do CoW, and then have to perform multiple bmap btree expansions.
Furthermore, the BUI recovery routine doesn't reserve /any/ blocks to
handle btree splits, so log recovery fails after our first error causes
the filesystem to go down.

Therefore, refactor the transaction block reservation macros until we
have a macro that works for our deferred (re)mapping activities, and fix
both problems by using that macro.

With 1k blocks we can hit this fairly often in g/187 if the scratch fs
is big enough.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Darrick J. Wong 2017-04-12 12:26:07 -07:00
parent e20c8a517f
commit fe0be23e68
3 changed files with 37 additions and 9 deletions
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23
fs/xfs/libxfs/xfs_trans_space.h
View file

@ -21,8 +21,20 @@
/*
* Components of space reservations.
*/
/* Worst case number of rmaps that can be held in a block. */
#define XFS_MAX_CONTIG_RMAPS_PER_BLOCK(mp) \
(((mp)->m_rmap_mxr[0]) - ((mp)->m_rmap_mnr[0]))
/* Adding one rmap could split every level up to the top of the tree. */
#define XFS_RMAPADD_SPACE_RES(mp) ((mp)->m_rmap_maxlevels)
/* Blocks we might need to add "b" rmaps to a tree. */
#define XFS_NRMAPADD_SPACE_RES(mp, b)\
(((b + XFS_MAX_CONTIG_RMAPS_PER_BLOCK(mp) - 1) / \
XFS_MAX_CONTIG_RMAPS_PER_BLOCK(mp)) * \
XFS_RMAPADD_SPACE_RES(mp))
#define XFS_MAX_CONTIG_EXTENTS_PER_BLOCK(mp) \
(((mp)->m_alloc_mxr[0]) - ((mp)->m_alloc_mnr[0]))
#define XFS_EXTENTADD_SPACE_RES(mp,w) (XFS_BM_MAXLEVELS(mp,w) - 1)
@ -30,13 +42,12 @@
(((b + XFS_MAX_CONTIG_EXTENTS_PER_BLOCK(mp) - 1) / \
XFS_MAX_CONTIG_EXTENTS_PER_BLOCK(mp)) * \
XFS_EXTENTADD_SPACE_RES(mp,w))
/* Blocks we might need to add "b" mappings & rmappings to a file. */
#define XFS_SWAP_RMAP_SPACE_RES(mp,b,w)\
(((b + XFS_MAX_CONTIG_EXTENTS_PER_BLOCK(mp) - 1) / \
XFS_MAX_CONTIG_EXTENTS_PER_BLOCK(mp)) * \
XFS_EXTENTADD_SPACE_RES(mp,w) + \
((b + XFS_MAX_CONTIG_RMAPS_PER_BLOCK(mp) - 1) / \
XFS_MAX_CONTIG_RMAPS_PER_BLOCK(mp)) * \
(mp)->m_rmap_maxlevels)
(XFS_NEXTENTADD_SPACE_RES((mp), (b), (w)) + \
XFS_NRMAPADD_SPACE_RES((mp), (b)))
#define XFS_DAENTER_1B(mp,w) \
((w) == XFS_DATA_FORK ? (mp)->m_dir_geo->fsbcount : 1)
#define XFS_DAENTER_DBS(mp,w) \

5
fs/xfs/xfs_bmap_item.c
View file

@ -34,6 +34,8 @@
#include "xfs_bmap.h"
#include "xfs_icache.h"
#include "xfs_trace.h"
#include "xfs_bmap_btree.h"
#include "xfs_trans_space.h"
kmem_zone_t *xfs_bui_zone;
@ -447,7 +449,8 @@ xfs_bui_recover(
return -EIO;
}
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp);
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate,
XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK), 0, 0, &tp);
if (error)
return error;
budp = xfs_trans_get_bud(tp, buip);

18
fs/xfs/xfs_reflink.c
View file

@ -705,8 +705,22 @@ xfs_reflink_end_cow(
offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
end_fsb = XFS_B_TO_FSB(ip->i_mount, offset + count);
/* Start a rolling transaction to switch the mappings */
resblks = XFS_EXTENTADD_SPACE_RES(ip->i_mount, XFS_DATA_FORK);
/*
* Start a rolling transaction to switch the mappings. We're
* unlikely ever to have to remap 16T worth of single-block
* extents, so just cap the worst case extent count to 2^32-1.
* Stick a warning in just in case, and avoid 64-bit division.
*/
BUILD_BUG_ON(MAX_RW_COUNT > UINT_MAX);
if (end_fsb - offset_fsb > UINT_MAX) {
error = -EFSCORRUPTED;
xfs_force_shutdown(ip->i_mount, SHUTDOWN_CORRUPT_INCORE);
ASSERT(0);
goto out;
}
resblks = XFS_NEXTENTADD_SPACE_RES(ip->i_mount,
(unsigned int)(end_fsb - offset_fsb),
XFS_DATA_FORK);
error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_write,
resblks, 0, 0, &tp);
if (error)