From 8c1903d3081ab7c416f1bbc7905f37a265d5e2e9 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Fri, 29 May 2015 07:39:34 +1000 Subject: [PATCH] xfs: inode and free block counters need to use __percpu_counter_compare Because the counters use a custom batch size, the comparison functions need to be aware of that batch size otherwise the comparison does not work correctly. This leads to ASSERT failures on generic/027 like this: XFS: Assertion failed: 0, file: fs/xfs/xfs_mount.c, line: 1099 ------------[ cut here ]------------ .... Call Trace: [] xfs_mod_icount+0x99/0xc0 [] xfs_trans_unreserve_and_mod_sb+0x28b/0x5b0 [] xfs_log_commit_cil+0x321/0x580 [] xfs_trans_commit+0xb7/0x260 [] xfs_bmap_finish+0xcd/0x1b0 [] xfs_inactive_ifree+0x1e1/0x250 [] xfs_inactive+0x130/0x200 [] xfs_fs_evict_inode+0x91/0xf0 [] evict+0xb8/0x190 [] iput+0x18b/0x1f0 [] do_unlinkat+0x1f3/0x320 [] ? filp_close+0x5a/0x80 [] SyS_unlinkat+0x1b/0x40 [] system_call_fastpath+0x12/0x71 This is a regression introduced by commit 501ab32 ("xfs: use generic percpu counters for inode counter"). This patch fixes the same problem for both the inode counter and the free block counter in the superblocks. Signed-off-by: Dave Chinner Reviewed-by: Brian Foster Signed-off-by: Dave Chinner --- fs/xfs/xfs_mount.c | 34 ++++++++++++++++++++-------------- 1 file changed, 20 insertions(+), 14 deletions(-) diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c index 2ce7ee3b4ec1..6f23fbdfb365 100644 --- a/fs/xfs/xfs_mount.c +++ b/fs/xfs/xfs_mount.c @@ -1084,14 +1084,18 @@ xfs_log_sbcount(xfs_mount_t *mp) return xfs_sync_sb(mp, true); } +/* + * Deltas for the inode count are +/-64, hence we use a large batch size + * of 128 so we don't need to take the counter lock on every update. + */ +#define XFS_ICOUNT_BATCH 128 int xfs_mod_icount( struct xfs_mount *mp, int64_t delta) { - /* deltas are +/-64, hence the large batch size of 128. */ - __percpu_counter_add(&mp->m_icount, delta, 128); - if (percpu_counter_compare(&mp->m_icount, 0) < 0) { + __percpu_counter_add(&mp->m_icount, delta, XFS_ICOUNT_BATCH); + if (__percpu_counter_compare(&mp->m_icount, 0, XFS_ICOUNT_BATCH) < 0) { ASSERT(0); percpu_counter_add(&mp->m_icount, -delta); return -EINVAL; @@ -1113,6 +1117,14 @@ xfs_mod_ifree( return 0; } +/* + * Deltas for the block count can vary from 1 to very large, but lock contention + * only occurs on frequent small block count updates such as in the delayed + * allocation path for buffered writes (page a time updates). Hence we set + * a large batch count (1024) to minimise global counter updates except when + * we get near to ENOSPC and we have to be very accurate with our updates. + */ +#define XFS_FDBLOCKS_BATCH 1024 int xfs_mod_fdblocks( struct xfs_mount *mp, @@ -1151,25 +1163,19 @@ xfs_mod_fdblocks( * Taking blocks away, need to be more accurate the closer we * are to zero. * - * batch size is set to a maximum of 1024 blocks - if we are - * allocating of freeing extents larger than this then we aren't - * going to be hammering the counter lock so a lock per update - * is not a problem. - * * If the counter has a value of less than 2 * max batch size, * then make everything serialise as we are real close to * ENOSPC. */ -#define __BATCH 1024 - if (percpu_counter_compare(&mp->m_fdblocks, 2 * __BATCH) < 0) + if (__percpu_counter_compare(&mp->m_fdblocks, 2 * XFS_FDBLOCKS_BATCH, + XFS_FDBLOCKS_BATCH) < 0) batch = 1; else - batch = __BATCH; -#undef __BATCH + batch = XFS_FDBLOCKS_BATCH; __percpu_counter_add(&mp->m_fdblocks, delta, batch); - if (percpu_counter_compare(&mp->m_fdblocks, - XFS_ALLOC_SET_ASIDE(mp)) >= 0) { + if (__percpu_counter_compare(&mp->m_fdblocks, XFS_ALLOC_SET_ASIDE(mp), + XFS_FDBLOCKS_BATCH) >= 0) { /* we had space! */ return 0; } -- 2.20.1