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Message-ID: <4746DB43.7060304@openvz.org>
Date: Fri, 23 Nov 2007 16:53:07 +0300
From: Pavel Emelyanov <xemul@...nvz.org>
To: Hugh Dickins <hugh@...itas.com>
CC: Andrew Morton <akpm@...l.org>, Linux MM <linux-mm@...ck.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
devel@...nvz.org
Subject: Re: [PATCH][SHMEM] Factor out sbi->free_inodes manipulations
Hugh Dickins wrote:
> Looks good, but we can save slightly more there (depending on config),
> and I found your inc/dec names a little confusing, since the count is
> going the other way: how do you feel about this version? (I'd like it
This is perfect =) Thanks for the masterclass!
> better if those helpers could take a struct inode *, but they cannot.)
> Hugh
>
>
> From: Pavel Emelyanov <xemul@...nvz.org>
>
> The shmem_sb_info structure has a number of free_inodes. This
> value is altered in appropriate places under spinlock and with
> the sbi->max_inodes != 0 check.
>
> Consolidate these manipulations into two helpers.
>
> This is minus 42 bytes of shmem.o and minus 4 :) lines of code.
>
> Signed-off-by: Pavel Emelyanov <xemul@...nvz.org>
> Signed-off-by: Hugh Dickins <hugh@...itas.com>
> ---
>
> mm/shmem.c | 72 ++++++++++++++++++++++++---------------------------
> 1 file changed, 34 insertions(+), 38 deletions(-)
>
> --- 2.6.24-rc3/mm/shmem.c 2007-11-07 04:21:45.000000000 +0000
> +++ linux/mm/shmem.c 2007-11-23 12:43:28.000000000 +0000
> @@ -207,6 +207,31 @@ static void shmem_free_blocks(struct ino
> }
> }
>
> +static int shmem_reserve_inode(struct super_block *sb)
> +{
> + struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
> + if (sbinfo->max_inodes) {
> + spin_lock(&sbinfo->stat_lock);
> + if (!sbinfo->free_inodes) {
> + spin_unlock(&sbinfo->stat_lock);
> + return -ENOMEM;
> + }
> + sbinfo->free_inodes--;
> + spin_unlock(&sbinfo->stat_lock);
> + }
> + return 0;
> +}
> +
> +static void shmem_free_inode(struct super_block *sb)
> +{
> + struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
> + if (sbinfo->max_inodes) {
> + spin_lock(&sbinfo->stat_lock);
> + sbinfo->free_inodes++;
> + spin_unlock(&sbinfo->stat_lock);
> + }
> +}
> +
> /*
> * shmem_recalc_inode - recalculate the size of an inode
> *
> @@ -762,7 +787,6 @@ static int shmem_notify_change(struct de
>
> static void shmem_delete_inode(struct inode *inode)
> {
> - struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
> struct shmem_inode_info *info = SHMEM_I(inode);
>
> if (inode->i_op->truncate == shmem_truncate) {
> @@ -777,11 +801,7 @@ static void shmem_delete_inode(struct in
> }
> }
> BUG_ON(inode->i_blocks);
> - if (sbinfo->max_inodes) {
> - spin_lock(&sbinfo->stat_lock);
> - sbinfo->free_inodes++;
> - spin_unlock(&sbinfo->stat_lock);
> - }
> + shmem_free_inode(inode->i_sb);
> clear_inode(inode);
> }
>
> @@ -1398,15 +1418,8 @@ shmem_get_inode(struct super_block *sb,
> struct shmem_inode_info *info;
> struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
>
> - if (sbinfo->max_inodes) {
> - spin_lock(&sbinfo->stat_lock);
> - if (!sbinfo->free_inodes) {
> - spin_unlock(&sbinfo->stat_lock);
> - return NULL;
> - }
> - sbinfo->free_inodes--;
> - spin_unlock(&sbinfo->stat_lock);
> - }
> + if (shmem_reserve_inode(sb))
> + return NULL;
>
> inode = new_inode(sb);
> if (inode) {
> @@ -1450,11 +1463,8 @@ shmem_get_inode(struct super_block *sb,
> NULL);
> break;
> }
> - } else if (sbinfo->max_inodes) {
> - spin_lock(&sbinfo->stat_lock);
> - sbinfo->free_inodes++;
> - spin_unlock(&sbinfo->stat_lock);
> - }
> + } else
> + shmem_free_inode(sb);
> return inode;
> }
>
> @@ -1797,22 +1807,14 @@ static int shmem_create(struct inode *di
> static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
> {
> struct inode *inode = old_dentry->d_inode;
> - struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
>
> /*
> * No ordinary (disk based) filesystem counts links as inodes;
> * but each new link needs a new dentry, pinning lowmem, and
> * tmpfs dentries cannot be pruned until they are unlinked.
> */
> - if (sbinfo->max_inodes) {
> - spin_lock(&sbinfo->stat_lock);
> - if (!sbinfo->free_inodes) {
> - spin_unlock(&sbinfo->stat_lock);
> - return -ENOSPC;
> - }
> - sbinfo->free_inodes--;
> - spin_unlock(&sbinfo->stat_lock);
> - }
> + if (shmem_reserve_inode(inode->i_sb))
> + return -ENOSPC;
>
> dir->i_size += BOGO_DIRENT_SIZE;
> inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
> @@ -1827,14 +1829,8 @@ static int shmem_unlink(struct inode *di
> {
> struct inode *inode = dentry->d_inode;
>
> - if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) {
> - struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
> - if (sbinfo->max_inodes) {
> - spin_lock(&sbinfo->stat_lock);
> - sbinfo->free_inodes++;
> - spin_unlock(&sbinfo->stat_lock);
> - }
> - }
> + if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
> + shmem_free_inode(inode->i_sb);
>
> dir->i_size -= BOGO_DIRENT_SIZE;
> inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
>
-
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