lkml.org 
[lkml]   [2011]   [May]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    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;

    \
     
     \ /
      Last update: 2011-05-31 02:57    [W:0.025 / U:150.536 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site