From 9bc08a45fb117c696e4940cfa1208cb1cc7a2f25 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Thu, 2 Sep 2010 15:14:38 +1000 Subject: [PATCH 1/4] xfs: improve buffer cache hash scalability When doing large parallel file creates on a 16p machines, large amounts of time is being spent in _xfs_buf_find(). A system wide profile with perf top shows this: 1134740.00 19.3% _xfs_buf_find 733142.00 12.5% __ticket_spin_lock The problem is that the hash contains 45,000 buffers, and the hash table width is only 256 buffers. That means we've got around 200 buffers per chain, and searching it is quite expensive. The hash table size needs to increase. Secondly, every time we do a lookup, we promote the buffer we find to the head of the hash chain. This is causing cachelines to be dirtied and causes invalidation of cachelines across all CPUs that may have walked the hash chain recently. hence every walk of the hash chain is effectively a cold cache walk. Remove the promotion to avoid this invalidation. The results are: 1045043.00 21.2% __ticket_spin_lock 326184.00 6.6% _xfs_buf_find A 70% drop in the CPU usage when looking up buffers. Unfortunately that does not result in an increase in performance underthis workload as contention on the inode_lock soaks up most of the reduction in CPU usage. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig --- fs/xfs/linux-2.6/xfs_buf.c | 8 +------- fs/xfs/linux-2.6/xfs_buf.h | 1 - 2 files changed, 1 insertion(+), 8 deletions(-) diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c index ea79072f5210..d72cf2bb054a 100644 --- a/fs/xfs/linux-2.6/xfs_buf.c +++ b/fs/xfs/linux-2.6/xfs_buf.c @@ -440,12 +440,7 @@ _xfs_buf_find( ASSERT(btp == bp->b_target); if (bp->b_file_offset == range_base && bp->b_buffer_length == range_length) { - /* - * If we look at something, bring it to the - * front of the list for next time. - */ atomic_inc(&bp->b_hold); - list_move(&bp->b_hash_list, &hash->bh_list); goto found; } } @@ -1443,8 +1438,7 @@ xfs_alloc_bufhash( { unsigned int i; - btp->bt_hashshift = external ? 3 : 8; /* 8 or 256 buckets */ - btp->bt_hashmask = (1 << btp->bt_hashshift) - 1; + btp->bt_hashshift = external ? 3 : 12; /* 8 or 4096 buckets */ btp->bt_hash = kmem_zalloc_large((1 << btp->bt_hashshift) * sizeof(xfs_bufhash_t)); for (i = 0; i < (1 << btp->bt_hashshift); i++) { diff --git a/fs/xfs/linux-2.6/xfs_buf.h b/fs/xfs/linux-2.6/xfs_buf.h index d072e5ff923b..2a05614f0b92 100644 --- a/fs/xfs/linux-2.6/xfs_buf.h +++ b/fs/xfs/linux-2.6/xfs_buf.h @@ -137,7 +137,6 @@ typedef struct xfs_buftarg { size_t bt_smask; /* per device buffer hash table */ - uint bt_hashmask; uint bt_hashshift; xfs_bufhash_t *bt_hash; From 23963e54ce187ca6e907c83176c15508b0f6e60d Mon Sep 17 00:00:00 2001 From: Arkadiusz Mi?kiewicz Date: Thu, 26 Aug 2010 10:19:43 +0000 Subject: [PATCH 2/4] xfs: Disallow 32bit project quota id Currently on-disk structure is able to keep only 16bit project quota id, so disallow 32bit ones. This fixes a problem where parts of kernel structures holding project quota id are 32bit while parts (on-disk) are 16bit variables which causes project quota member files to be inaccessible for some operations (like mv/rm). Signed-off-by: Arkadiusz Mi?kiewicz Reviewed-by: Christoph Hellwig Signed-off-by: Alex Elder --- fs/xfs/linux-2.6/xfs_ioctl.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/fs/xfs/linux-2.6/xfs_ioctl.c b/fs/xfs/linux-2.6/xfs_ioctl.c index 237f5ffb2ee8..4fec427b83ef 100644 --- a/fs/xfs/linux-2.6/xfs_ioctl.c +++ b/fs/xfs/linux-2.6/xfs_ioctl.c @@ -906,6 +906,13 @@ xfs_ioctl_setattr( if (XFS_FORCED_SHUTDOWN(mp)) return XFS_ERROR(EIO); + /* + * Disallow 32bit project ids because on-disk structure + * is 16bit only. + */ + if ((mask & FSX_PROJID) && (fa->fsx_projid > (__uint16_t)-1)) + return XFS_ERROR(EINVAL); + /* * If disk quotas is on, we make sure that the dquots do exist on disk, * before we start any other transactions. Trying to do this later From 72656c46f50b8dfe50e15793692982e636e3df20 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Fri, 3 Sep 2010 12:19:33 +1000 Subject: [PATCH 3/4] xfs: prevent 32bit overflow in space reservation If we attempt to preallocate more than 2^32 blocks of space in a single syscall, the transaction block reservation will overflow leading to a hangs in the superblock block accounting code. This is trivially reproduced with xfs_io. Fix the problem by capping the allocation reservation to the maximum number of blocks a single xfs_bmapi() call can allocate (2^21 blocks). Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig --- fs/xfs/xfs_vnodeops.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c index 66d585c6917c..4c7c7bfb2b2f 100644 --- a/fs/xfs/xfs_vnodeops.c +++ b/fs/xfs/xfs_vnodeops.c @@ -2299,15 +2299,22 @@ xfs_alloc_file_space( e = allocatesize_fsb; } + /* + * The transaction reservation is limited to a 32-bit block + * count, hence we need to limit the number of blocks we are + * trying to reserve to avoid an overflow. We can't allocate + * more than @nimaps extents, and an extent is limited on disk + * to MAXEXTLEN (21 bits), so use that to enforce the limit. + */ + resblks = min_t(xfs_fileoff_t, (e - s), (MAXEXTLEN * nimaps)); if (unlikely(rt)) { - resrtextents = qblocks = (uint)(e - s); + resrtextents = qblocks = resblks; resrtextents /= mp->m_sb.sb_rextsize; resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0); quota_flag = XFS_QMOPT_RES_RTBLKS; } else { resrtextents = 0; - resblks = qblocks = \ - XFS_DIOSTRAT_SPACE_RES(mp, (uint)(e - s)); + resblks = qblocks = XFS_DIOSTRAT_SPACE_RES(mp, resblks); quota_flag = XFS_QMOPT_RES_REGBLKS; } From 9af25465081480a75824fd7a16a37a5cfebeede9 Mon Sep 17 00:00:00 2001 From: Tao Ma Date: Mon, 30 Aug 2010 02:44:03 +0000 Subject: [PATCH 4/4] xfs: Make fiemap work with sparse files In xfs_vn_fiemap, we set bvm_count to fi_extent_max + 1 and want to return fi_extent_max extents, but actually it won't work for a sparse file. The reason is that in xfs_getbmap we will calculate holes and set it in 'out', while out is malloced by bmv_count(fi_extent_max+1) which didn't consider holes. So in the worst case, if 'out' vector looks like [hole, extent, hole, extent, hole, ... hole, extent, hole], we will only return half of fi_extent_max extents. This patch add a new parameter BMV_IF_NO_HOLES for bvm_iflags. So with this flags, we don't use our 'out' in xfs_getbmap for a hole. The solution is a bit ugly by just don't increasing index of 'out' vector. I felt that it is not easy to skip it at the very beginning since we have the complicated check and some function like xfs_getbmapx_fix_eof_hole to adjust 'out'. Cc: Dave Chinner Signed-off-by: Tao Ma Signed-off-by: Alex Elder --- fs/xfs/linux-2.6/xfs_iops.c | 2 +- fs/xfs/xfs_bmap.c | 14 +++++++++++++- fs/xfs/xfs_fs.h | 4 +++- 3 files changed, 17 insertions(+), 3 deletions(-) diff --git a/fs/xfs/linux-2.6/xfs_iops.c b/fs/xfs/linux-2.6/xfs_iops.c index 68be25dcd301..b1fc2a6bfe83 100644 --- a/fs/xfs/linux-2.6/xfs_iops.c +++ b/fs/xfs/linux-2.6/xfs_iops.c @@ -664,7 +664,7 @@ xfs_vn_fiemap( fieinfo->fi_extents_max + 1; bm.bmv_count = min_t(__s32, bm.bmv_count, (PAGE_SIZE * 16 / sizeof(struct getbmapx))); - bm.bmv_iflags = BMV_IF_PREALLOC; + bm.bmv_iflags = BMV_IF_PREALLOC | BMV_IF_NO_HOLES; if (fieinfo->fi_flags & FIEMAP_FLAG_XATTR) bm.bmv_iflags |= BMV_IF_ATTRFORK; if (!(fieinfo->fi_flags & FIEMAP_FLAG_SYNC)) diff --git a/fs/xfs/xfs_bmap.c b/fs/xfs/xfs_bmap.c index 23f14e595c18..f90dadd5a968 100644 --- a/fs/xfs/xfs_bmap.c +++ b/fs/xfs/xfs_bmap.c @@ -5533,12 +5533,24 @@ xfs_getbmap( map[i].br_startblock)) goto out_free_map; - nexleft--; bmv->bmv_offset = out[cur_ext].bmv_offset + out[cur_ext].bmv_length; bmv->bmv_length = max_t(__int64_t, 0, bmvend - bmv->bmv_offset); + + /* + * In case we don't want to return the hole, + * don't increase cur_ext so that we can reuse + * it in the next loop. + */ + if ((iflags & BMV_IF_NO_HOLES) && + map[i].br_startblock == HOLESTARTBLOCK) { + memset(&out[cur_ext], 0, sizeof(out[cur_ext])); + continue; + } + + nexleft--; bmv->bmv_entries++; cur_ext++; } diff --git a/fs/xfs/xfs_fs.h b/fs/xfs/xfs_fs.h index 7cf7220e7d5f..87c2e9d02288 100644 --- a/fs/xfs/xfs_fs.h +++ b/fs/xfs/xfs_fs.h @@ -114,8 +114,10 @@ struct getbmapx { #define BMV_IF_NO_DMAPI_READ 0x2 /* Do not generate DMAPI read event */ #define BMV_IF_PREALLOC 0x4 /* rtn status BMV_OF_PREALLOC if req */ #define BMV_IF_DELALLOC 0x8 /* rtn status BMV_OF_DELALLOC if req */ +#define BMV_IF_NO_HOLES 0x10 /* Do not return holes */ #define BMV_IF_VALID \ - (BMV_IF_ATTRFORK|BMV_IF_NO_DMAPI_READ|BMV_IF_PREALLOC|BMV_IF_DELALLOC) + (BMV_IF_ATTRFORK|BMV_IF_NO_DMAPI_READ|BMV_IF_PREALLOC| \ + BMV_IF_DELALLOC|BMV_IF_NO_HOLES) /* bmv_oflags values - returned for each non-header segment */ #define BMV_OF_PREALLOC 0x1 /* segment = unwritten pre-allocation */