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| author | Dave Chinner <dchinner@redhat.com> | 2013-12-12 16:34:36 +1100 |
|---|---|---|
| committer | Ben Myers <bpm@sgi.com> | 2013-12-17 09:30:12 -0600 |
| commit | 33177f05364c6cd13b06d0f3500dad07cf4647c2 (patch) | |
| tree | 53737ce77a1e4bef9bbe5b38d4d6ec06d6f60da0 /fs/xfs | |
| parent | 83a0adc3f93aae4ab9c59113e3145c7bdb2b4a8c (diff) | |
| download | linux-33177f05364c6cd13b06d0f3500dad07cf4647c2.tar.gz | |
xfs: swalloc doesn't align allocations properly
When swalloc is specified as a mount option, allocations are supposed to be aligned to the stripe width rather than the stripe unit of the underlying filesystem. However, it does not do this. What the implementation does is round up the allocation size to a stripe width, hence ensuring that all allocations span a full stripe width. It does not, however, ensure that that allocation is aligned to a stripe width, and hence the allocations can span multiple underlying stripes and so still see RMW cycles for things like direct IO on MD RAID. So, if the swalloc mount option is set, change the allocation alignment in xfs_bmap_btalloc() to use the stripe width rather than the stripe unit. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Ben Myers <bpm@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
Diffstat (limited to 'fs/xfs')
| -rw-r--r-- | fs/xfs/xfs_bmap.c | 23 |
1 files changed, 17 insertions, 6 deletions
diff --git a/fs/xfs/xfs_bmap.c b/fs/xfs/xfs_bmap.c index 8401f11f378f..3b2c14b6f0fb 100644 --- a/fs/xfs/xfs_bmap.c +++ b/fs/xfs/xfs_bmap.c @@ -3648,10 +3648,19 @@ xfs_bmap_btalloc( int isaligned; int tryagain; int error; + int stripe_align; ASSERT(ap->length); mp = ap->ip->i_mount; + + /* stripe alignment for allocation is determined by mount parameters */ + stripe_align = 0; + if (mp->m_swidth && (mp->m_flags & XFS_MOUNT_SWALLOC)) + stripe_align = mp->m_swidth; + else if (mp->m_dalign) + stripe_align = mp->m_dalign; + align = ap->userdata ? xfs_get_extsz_hint(ap->ip) : 0; if (unlikely(align)) { error = xfs_bmap_extsize_align(mp, &ap->got, &ap->prev, @@ -3660,6 +3669,8 @@ xfs_bmap_btalloc( ASSERT(!error); ASSERT(ap->length); } + + nullfb = *ap->firstblock == NULLFSBLOCK; fb_agno = nullfb ? NULLAGNUMBER : XFS_FSB_TO_AGNO(mp, *ap->firstblock); if (nullfb) { @@ -3735,7 +3746,7 @@ xfs_bmap_btalloc( */ if (!ap->flist->xbf_low && ap->aeof) { if (!ap->offset) { - args.alignment = mp->m_dalign; + args.alignment = stripe_align; atype = args.type; isaligned = 1; /* @@ -3760,13 +3771,13 @@ xfs_bmap_btalloc( * of minlen+alignment+slop doesn't go up * between the calls. */ - if (blen > mp->m_dalign && blen <= args.maxlen) - nextminlen = blen - mp->m_dalign; + if (blen > stripe_align && blen <= args.maxlen) + nextminlen = blen - stripe_align; else nextminlen = args.minlen; - if (nextminlen + mp->m_dalign > args.minlen + 1) + if (nextminlen + stripe_align > args.minlen + 1) args.minalignslop = - nextminlen + mp->m_dalign - + nextminlen + stripe_align - args.minlen - 1; else args.minalignslop = 0; @@ -3788,7 +3799,7 @@ xfs_bmap_btalloc( */ args.type = atype; args.fsbno = ap->blkno; - args.alignment = mp->m_dalign; + args.alignment = stripe_align; args.minlen = nextminlen; args.minalignslop = 0; isaligned = 1; |