Commit fe0be23e authored by Darrick J. Wong's avatar Darrick J. Wong
Browse files

xfs: reserve enough blocks to handle btree splits when remapping 



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: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
parent e20c8a51

fs/xfs/libxfs/xfs_trans_space.h

+17 −6
Original line number Diff line number Diff line
@@ -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)	\

fs/xfs/xfs_bmap_item.c

+4 −1
Original line number Diff line number Diff line
@@ -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);

fs/xfs/xfs_reflink.c

+16 −2
Original line number Diff line number Diff line
@@ -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)

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