1 files changed, 17 insertions, 23 deletions

diff --git a/mm/shmem.c b/mm/shmem.c
index f65f84062db5..0618fdad406c 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -28,6 +28,7 @@
 #include <linux/file.h>
 #include <linux/mm.h>
 #include <linux/module.h>
+#include <linux/percpu_counter.h>
 #include <linux/swap.h>
 
 static struct vfsmount *shm_mnt;
@@ -233,10 +234,10 @@ static void shmem_free_blocks(struct inode *inode, long pages)
 {
         struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
         if (sbinfo->max_blocks) {
-                spin_lock(&sbinfo->stat_lock);
-                sbinfo->free_blocks += pages;
+                percpu_counter_add(&sbinfo->used_blocks, -pages);
+                spin_lock(&inode->i_lock);
                 inode->i_blocks -= pages*BLOCKS_PER_PAGE;
-                spin_unlock(&sbinfo->stat_lock);
+                spin_unlock(&inode->i_lock);
         }
 }
 
@@ -416,19 +417,17 @@ static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long
                 if (sgp == SGP_READ)
                         return shmem_swp_map(ZERO_PAGE(0));
                 /*
-                 * Test free_blocks against 1 not 0, since we have 1 data
+                 * Test used_blocks against 1 less max_blocks, since we have 1 data
                  * page (and perhaps indirect index pages) yet to allocate:
                  * a waste to allocate index if we cannot allocate data.
                  */
                 if (sbinfo->max_blocks) {
-                        spin_lock(&sbinfo->stat_lock);
-                        if (sbinfo->free_blocks <= 1) {
-                                spin_unlock(&sbinfo->stat_lock);
+                        if (percpu_counter_compare(&sbinfo->used_blocks, (sbinfo->max_blocks - 1)) > 0)
                                 return ERR_PTR(-ENOSPC);
-                        }
-                        sbinfo->free_blocks--;
+                        percpu_counter_inc(&sbinfo->used_blocks);
+                        spin_lock(&inode->i_lock);
                         inode->i_blocks += BLOCKS_PER_PAGE;
-                        spin_unlock(&sbinfo->stat_lock);
+                        spin_unlock(&inode->i_lock);
                 }
 
                 spin_unlock(&info->lock);
@@ -1387,17 +1386,16 @@ repeat:
                 shmem_swp_unmap(entry);
                 sbinfo = SHMEM_SB(inode->i_sb);
                 if (sbinfo->max_blocks) {
-                        spin_lock(&sbinfo->stat_lock);
-                        if (sbinfo->free_blocks == 0 ||
+                        if ((percpu_counter_compare(&sbinfo->used_blocks, sbinfo->max_blocks) > 0) ||
                             shmem_acct_block(info->flags)) {
-                                spin_unlock(&sbinfo->stat_lock);
                                 spin_unlock(&info->lock);
                                 error = -ENOSPC;
                                 goto failed;
                         }
-                        sbinfo->free_blocks--;
+                        percpu_counter_inc(&sbinfo->used_blocks);
+                        spin_lock(&inode->i_lock);
                         inode->i_blocks += BLOCKS_PER_PAGE;
-                        spin_unlock(&sbinfo->stat_lock);
+                        spin_unlock(&inode->i_lock);
                 } else if (shmem_acct_block(info->flags)) {
                         spin_unlock(&info->lock);
                         error = -ENOSPC;
@@ -1791,17 +1789,16 @@ static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
         buf->f_type = TMPFS_MAGIC;
         buf->f_bsize = PAGE_CACHE_SIZE;
         buf->f_namelen = NAME_MAX;
-        spin_lock(&sbinfo->stat_lock);
         if (sbinfo->max_blocks) {
                 buf->f_blocks = sbinfo->max_blocks;
-                buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
+                buf->f_bavail = buf->f_bfree =
+                                sbinfo->max_blocks - percpu_counter_sum(&sbinfo->used_blocks);
         }
         if (sbinfo->max_inodes) {
                 buf->f_files = sbinfo->max_inodes;
                 buf->f_ffree = sbinfo->free_inodes;
         }
         /* else leave those fields 0 like simple_statfs */
-        spin_unlock(&sbinfo->stat_lock);
         return 0;
 }
 
@@ -2242,7 +2239,6 @@ static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
 {
         struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
         struct shmem_sb_info config = *sbinfo;
-        unsigned long blocks;
         unsigned long inodes;
         int error = -EINVAL;
 
@@ -2250,9 +2246,8 @@ static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
                 return error;
 
         spin_lock(&sbinfo->stat_lock);
-        blocks = sbinfo->max_blocks - sbinfo->free_blocks;
         inodes = sbinfo->max_inodes - sbinfo->free_inodes;
-        if (config.max_blocks < blocks)
+        if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0)
                 goto out;
         if (config.max_inodes < inodes)
                 goto out;
@@ -2269,7 +2264,6 @@ static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
 
         error = 0;
         sbinfo->max_blocks  = config.max_blocks;
-        sbinfo->free_blocks = config.max_blocks - blocks;
         sbinfo->max_inodes  = config.max_inodes;
         sbinfo->free_inodes = config.max_inodes - inodes;
 
@@ -2344,7 +2338,7 @@ int shmem_fill_super(struct super_block *sb, void *data, int silent)
 #endif
 
         spin_lock_init(&sbinfo->stat_lock);
-        sbinfo->free_blocks = sbinfo->max_blocks;
+        percpu_counter_init(&sbinfo->used_blocks, 0);
         sbinfo->free_inodes = sbinfo->max_inodes;
 
         sb->s_maxbytes = SHMEM_MAX_BYTES;