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Date: Fri, 23 Nov 2007 13:41:55 +0000 (GMT)
From: Hugh Dickins <hugh@...itas.com>
To: Pavel Emelyanov <xemul@...nvz.org>
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
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
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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