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xfs: implement swapext for rmap filesystems
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Implement swapext for filesystems that have reverse mapping.  Back in
the reflink patches, we augmented the bmap code with a 'REMAP' flag
that updates only the bmbt and doesn't touch the allocator and
implemented log redo items for those two operations.  Now we can
rewrite extent swapping as a (looong) series of remap operations.

This is far less efficient than the fork swapping method implemented
in the past, so we only switch this on for rmap.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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Darrick J. Wong committed Oct 5, 2016
1 parent 39aff5f commit 1f08af5
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Showing 3 changed files with 173 additions and 3 deletions.
9 changes: 9 additions & 0 deletions fs/xfs/libxfs/xfs_trans_space.h
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Original file line number Diff line number Diff line change
Expand Up @@ -21,13 +21,22 @@
/*
* Components of space reservations.
*/
#define XFS_MAX_CONTIG_RMAPS_PER_BLOCK(mp) \
(((mp)->m_rmap_mxr[0]) - ((mp)->m_rmap_mnr[0]))
#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)
#define XFS_NEXTENTADD_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))
#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)
#define XFS_DAENTER_1B(mp,w) \
((w) == XFS_DATA_FORK ? (mp)->m_dir_geo->fsbcount : 1)
#define XFS_DAENTER_DBS(mp,w) \
Expand Down
162 changes: 159 additions & 3 deletions fs/xfs/xfs_bmap_util.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1580,6 +1580,13 @@ xfs_swap_extents_check_format(
if (ip->i_d.di_nextents < tip->i_d.di_nextents)
return -EINVAL;

/*
* If we have to use the (expensive) rmap swap method, we can
* handle any number of extents and any format.
*/
if (xfs_sb_version_hasrmapbt(&ip->i_mount->m_sb))
return 0;

/*
* if the target inode is in extent form and the temp inode is in btree
* form then we will end up with the target inode in the wrong format
Expand Down Expand Up @@ -1649,6 +1656,130 @@ xfs_swap_extent_flush(
return 0;
}

/*
* Move extents from one file to another, when rmap is enabled.
*/
STATIC int
xfs_swap_extent_rmap(
struct xfs_trans **tpp,
struct xfs_inode *ip,
struct xfs_inode *tip)
{
struct xfs_bmbt_irec irec;
struct xfs_bmbt_irec uirec;
struct xfs_bmbt_irec tirec;
xfs_fileoff_t offset_fsb;
xfs_fileoff_t end_fsb;
xfs_filblks_t count_fsb;
xfs_fsblock_t firstfsb;
struct xfs_defer_ops dfops;
int error;
xfs_filblks_t ilen;
xfs_filblks_t rlen;
int nimaps;
__uint64_t tip_flags2;

/*
* If the source file has shared blocks, we must flag the donor
* file as having shared blocks so that we get the shared-block
* rmap functions when we go to fix up the rmaps. The flags
* will be switch for reals later.
*/
tip_flags2 = tip->i_d.di_flags2;
if (ip->i_d.di_flags2 & XFS_DIFLAG2_REFLINK)
tip->i_d.di_flags2 |= XFS_DIFLAG2_REFLINK;

offset_fsb = 0;
end_fsb = XFS_B_TO_FSB(ip->i_mount, i_size_read(VFS_I(ip)));
count_fsb = (xfs_filblks_t)(end_fsb - offset_fsb);

while (count_fsb) {
/* Read extent from the donor file */
nimaps = 1;
error = xfs_bmapi_read(tip, offset_fsb, count_fsb, &tirec,
&nimaps, 0);
if (error)
goto out;
ASSERT(nimaps == 1);
ASSERT(tirec.br_startblock != DELAYSTARTBLOCK);

trace_xfs_swap_extent_rmap_remap(tip, &tirec);
ilen = tirec.br_blockcount;

/* Unmap the old blocks in the source file. */
while (tirec.br_blockcount) {
xfs_defer_init(&dfops, &firstfsb);
trace_xfs_swap_extent_rmap_remap_piece(tip, &tirec);

/* Read extent from the source file */
nimaps = 1;
error = xfs_bmapi_read(ip, tirec.br_startoff,
tirec.br_blockcount, &irec,
&nimaps, 0);
if (error)
goto out_defer;
ASSERT(nimaps == 1);
ASSERT(tirec.br_startoff == irec.br_startoff);
trace_xfs_swap_extent_rmap_remap_piece(ip, &irec);

/* Trim the extent. */
uirec = tirec;
uirec.br_blockcount = rlen = min_t(xfs_filblks_t,
tirec.br_blockcount,
irec.br_blockcount);
trace_xfs_swap_extent_rmap_remap_piece(tip, &uirec);

/* Remove the mapping from the donor file. */
error = xfs_bmap_unmap_extent((*tpp)->t_mountp, &dfops,
tip, &uirec);
if (error)
goto out_defer;

/* Remove the mapping from the source file. */
error = xfs_bmap_unmap_extent((*tpp)->t_mountp, &dfops,
ip, &irec);
if (error)
goto out_defer;

/* Map the donor file's blocks into the source file. */
error = xfs_bmap_map_extent((*tpp)->t_mountp, &dfops,
ip, &uirec);
if (error)
goto out_defer;

/* Map the source file's blocks into the donor file. */
error = xfs_bmap_map_extent((*tpp)->t_mountp, &dfops,
tip, &irec);
if (error)
goto out_defer;

error = xfs_defer_finish(tpp, &dfops, ip);
if (error)
goto out_defer;

tirec.br_startoff += rlen;
if (tirec.br_startblock != HOLESTARTBLOCK &&
tirec.br_startblock != DELAYSTARTBLOCK)
tirec.br_startblock += rlen;
tirec.br_blockcount -= rlen;
}

/* Roll on... */
count_fsb -= ilen;
offset_fsb += ilen;
}

tip->i_d.di_flags2 = tip_flags2;
return 0;

out_defer:
xfs_defer_cancel(&dfops);
out:
trace_xfs_swap_extent_rmap_error(ip, error, _RET_IP_);
tip->i_d.di_flags2 = tip_flags2;
return error;
}

/* Swap the extents of two files by swapping data forks. */
STATIC int
xfs_swap_extent_forks(
Expand Down Expand Up @@ -1799,6 +1930,7 @@ xfs_swap_extents(
int lock_flags;
struct xfs_ifork *cowfp;
__uint64_t f;
int resblks;

/*
* Lock the inodes against other IO, page faults and truncate to
Expand Down Expand Up @@ -1829,7 +1961,28 @@ xfs_swap_extents(
if (error)
goto out_unlock;

error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
/*
* Extent "swapping" with rmap requires a permanent reservation and
* a block reservation because it's really just a remap operation
* performed with log redo items!
*/
if (xfs_sb_version_hasrmapbt(&mp->m_sb)) {
/*
* Conceptually this shouldn't affect the shape of either
* bmbt, but since we atomically move extents one by one,
* we reserve enough space to rebuild both trees.
*/
resblks = XFS_SWAP_RMAP_SPACE_RES(mp,
XFS_IFORK_NEXTENTS(ip, XFS_DATA_FORK),
XFS_DATA_FORK) +
XFS_SWAP_RMAP_SPACE_RES(mp,
XFS_IFORK_NEXTENTS(tip, XFS_DATA_FORK),
XFS_DATA_FORK);
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks,
0, 0, &tp);
} else
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0,
0, 0, &tp);
if (error)
goto out_unlock;

Expand Down Expand Up @@ -1888,8 +2041,11 @@ xfs_swap_extents(
src_log_flags = XFS_ILOG_CORE;
target_log_flags = XFS_ILOG_CORE;

error = xfs_swap_extent_forks(tp, ip, tip, &src_log_flags,
&target_log_flags);
if (xfs_sb_version_hasrmapbt(&mp->m_sb))
error = xfs_swap_extent_rmap(&tp, ip, tip);
else
error = xfs_swap_extent_forks(tp, ip, tip, &src_log_flags,
&target_log_flags);
if (error)
goto out_trans_cancel;

Expand Down
5 changes: 5 additions & 0 deletions fs/xfs/xfs_trace.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3373,6 +3373,11 @@ DEFINE_INODE_EVENT(xfs_reflink_cancel_pending_cow);
DEFINE_INODE_IREC_EVENT(xfs_reflink_cancel_cow);
DEFINE_INODE_ERROR_EVENT(xfs_reflink_cancel_pending_cow_error);

/* rmap swapext tracepoints */
DEFINE_INODE_IREC_EVENT(xfs_swap_extent_rmap_remap);
DEFINE_INODE_IREC_EVENT(xfs_swap_extent_rmap_remap_piece);
DEFINE_INODE_ERROR_EVENT(xfs_swap_extent_rmap_error);

#endif /* _TRACE_XFS_H */

#undef TRACE_INCLUDE_PATH
Expand Down

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