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authorHugh Dickins <hughd@google.com>2011-07-25 17:12:26 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-07-25 20:57:10 -0700
commitd515afe88a32e567c550e3db914f3e378f86453a (patch)
tree0129002decdd5c1f8bcb521aacdba73e0d1699c3 /mm/shmem.c
parentd0823576bf4b8eafce1b56f98613465a0352a376 (diff)
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tmpfs: no need to use i_lock
2.6.36's 7e496299d4d2 ("tmpfs: make tmpfs scalable with percpu_counter for used blocks") 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> Acked-by: Tim Chen <tim.c.chen@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/shmem.c')
-rw-r--r--mm/shmem.c14
1 files changed, 6 insertions, 8 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index fcedf5464eb7..c1db11cf220d 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -241,9 +241,7 @@ static void shmem_free_blocks(struct inode *inode, long pages)
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(struct shmem_inode_info *info, unsigned long
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);
@@ -1421,9 +1417,7 @@ 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;
@@ -1434,8 +1428,10 @@ 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;
}
@@ -1449,8 +1445,10 @@ 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;
}
@@ -1480,10 +1478,10 @@ 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;