Messages in this thread Patch in this message | | | Date | Mon, 30 May 2011 17:55:44 -0700 (PDT) | From | Hugh Dickins <> | Subject | [PATCH 14/14] tmpfs: no need to use i_lock |
| |
2.6.36's 7e496299d4d2 to make tmpfs scalable with percpu_counter used inode->i_lock in place of sbinfo->stat_lock around i_blocks updates; but that was adverse to scalability, and unnecessary, since info->lock is already held there in the fast paths.
Remove those uses of i_lock, and add info->lock in the three error paths where it's then needed across shmem_free_blocks(). It's not actually needed across shmem_unacct_blocks(), but they're so often paired that it looks wrong to split them apart.
Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Tim Chen <tim.c.chen@linux.intel.com> --- mm/shmem.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-)
--- linux.orig/mm/shmem.c 2011-05-30 14:25:32.665536626 -0700 +++ linux/mm/shmem.c 2011-05-30 15:03:41.680887254 -0700 @@ -241,9 +241,7 @@ static void shmem_free_blocks(struct ino struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); if (sbinfo->max_blocks) { percpu_counter_add(&sbinfo->used_blocks, -pages); - spin_lock(&inode->i_lock); inode->i_blocks -= pages*BLOCKS_PER_PAGE; - spin_unlock(&inode->i_lock); } } @@ -432,9 +430,7 @@ static swp_entry_t *shmem_swp_alloc(stru sbinfo->max_blocks - 1) >= 0) return ERR_PTR(-ENOSPC); percpu_counter_inc(&sbinfo->used_blocks); - spin_lock(&inode->i_lock); inode->i_blocks += BLOCKS_PER_PAGE; - spin_unlock(&inode->i_lock); } spin_unlock(&info->lock); @@ -1420,9 +1416,7 @@ repeat: shmem_acct_block(info->flags)) goto nospace; percpu_counter_inc(&sbinfo->used_blocks); - spin_lock(&inode->i_lock); inode->i_blocks += BLOCKS_PER_PAGE; - spin_unlock(&inode->i_lock); } else if (shmem_acct_block(info->flags)) goto nospace; @@ -1433,8 +1427,10 @@ repeat: spin_unlock(&info->lock); filepage = shmem_alloc_page(gfp, info, idx); if (!filepage) { + spin_lock(&info->lock); shmem_unacct_blocks(info->flags, 1); shmem_free_blocks(inode, 1); + spin_unlock(&info->lock); error = -ENOMEM; goto failed; } @@ -1448,8 +1444,10 @@ repeat: current->mm, GFP_KERNEL); if (error) { page_cache_release(filepage); + spin_lock(&info->lock); shmem_unacct_blocks(info->flags, 1); shmem_free_blocks(inode, 1); + spin_unlock(&info->lock); filepage = NULL; goto failed; } @@ -1479,10 +1477,10 @@ repeat: * be done automatically. */ if (ret) { - spin_unlock(&info->lock); - page_cache_release(filepage); shmem_unacct_blocks(info->flags, 1); shmem_free_blocks(inode, 1); + spin_unlock(&info->lock); + page_cache_release(filepage); filepage = NULL; if (error) goto failed;
| |