1 files changed, 70 insertions, 73 deletions

diff --git a/mm/shmem.c b/mm/shmem.c
index 61574b8..e64fa72 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -6,8 +6,8 @@
  *		 2000-2001 Christoph Rohland
  *		 2000-2001 SAP AG
  *		 2002 Red Hat Inc.
- * Copyright (C) 2002-2004 Hugh Dickins.
- * Copyright (C) 2002-2004 VERITAS Software Corporation.
+ * Copyright (C) 2002-2005 Hugh Dickins.
+ * Copyright (C) 2002-2005 VERITAS Software Corporation.
  * Copyright (C) 2004 Andi Kleen, SuSE Labs
  *
  * Extended attribute support for tmpfs:
@@ -194,7 +194,7 @@ static DEFINE_SPINLOCK(shmem_swaplist_lock);
 static void shmem_free_blocks(struct inode *inode, long pages)
 {
 	struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
-	if (sbinfo) {
+	if (sbinfo->max_blocks) {
 		spin_lock(&sbinfo->stat_lock);
 		sbinfo->free_blocks += pages;
 		inode->i_blocks -= pages*BLOCKS_PER_PAGE;
@@ -357,7 +357,7 @@ static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long
 		 * page (and perhaps indirect index pages) yet to allocate:
 		 * a waste to allocate index if we cannot allocate data.
 		 */
-		if (sbinfo) {
+		if (sbinfo->max_blocks) {
 			spin_lock(&sbinfo->stat_lock);
 			if (sbinfo->free_blocks <= 1) {
 				spin_unlock(&sbinfo->stat_lock);
@@ -677,8 +677,8 @@ static void shmem_delete_inode(struct inode *inode)
 			spin_unlock(&shmem_swaplist_lock);
 		}
 	}
-	if (sbinfo) {
-		BUG_ON(inode->i_blocks);
+	BUG_ON(inode->i_blocks);
+	if (sbinfo->max_inodes) {
 		spin_lock(&sbinfo->stat_lock);
 		sbinfo->free_inodes++;
 		spin_unlock(&sbinfo->stat_lock);
@@ -1080,7 +1080,7 @@ repeat:
 	} else {
 		shmem_swp_unmap(entry);
 		sbinfo = SHMEM_SB(inode->i_sb);
-		if (sbinfo) {
+		if (sbinfo->max_blocks) {
 			spin_lock(&sbinfo->stat_lock);
 			if (sbinfo->free_blocks == 0 ||
 			    shmem_acct_block(info->flags)) {
@@ -1269,7 +1269,7 @@ shmem_get_inode(struct super_block *sb, int mode, dev_t dev)
 	struct shmem_inode_info *info;
 	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
 
-	if (sbinfo) {
+	if (sbinfo->max_inodes) {
 		spin_lock(&sbinfo->stat_lock);
 		if (!sbinfo->free_inodes) {
 			spin_unlock(&sbinfo->stat_lock);
@@ -1319,7 +1319,7 @@ shmem_get_inode(struct super_block *sb, int mode, dev_t dev)
 			mpol_shared_policy_init(&info->policy);
 			break;
 		}
-	} else if (sbinfo) {
+	} else if (sbinfo->max_inodes) {
 		spin_lock(&sbinfo->stat_lock);
 		sbinfo->free_inodes++;
 		spin_unlock(&sbinfo->stat_lock);
@@ -1328,31 +1328,6 @@ shmem_get_inode(struct super_block *sb, int mode, dev_t dev)
 }
 
 #ifdef CONFIG_TMPFS
-
-static int shmem_set_size(struct shmem_sb_info *sbinfo,
-			  unsigned long max_blocks, unsigned long max_inodes)
-{
-	int error;
-	unsigned long blocks, inodes;
-
-	spin_lock(&sbinfo->stat_lock);
-	blocks = sbinfo->max_blocks - sbinfo->free_blocks;
-	inodes = sbinfo->max_inodes - sbinfo->free_inodes;
-	error = -EINVAL;
-	if (max_blocks < blocks)
-		goto out;
-	if (max_inodes < inodes)
-		goto out;
-	error = 0;
-	sbinfo->max_blocks  = max_blocks;
-	sbinfo->free_blocks = max_blocks - blocks;
-	sbinfo->max_inodes  = max_inodes;
-	sbinfo->free_inodes = max_inodes - inodes;
-out:
-	spin_unlock(&sbinfo->stat_lock);
-	return error;
-}
-
 static struct inode_operations shmem_symlink_inode_operations;
 static struct inode_operations shmem_symlink_inline_operations;
 
@@ -1607,15 +1582,17 @@ static int shmem_statfs(struct super_block *sb, struct kstatfs *buf)
 	buf->f_type = TMPFS_MAGIC;
 	buf->f_bsize = PAGE_CACHE_SIZE;
 	buf->f_namelen = NAME_MAX;
-	if (sbinfo) {
-		spin_lock(&sbinfo->stat_lock);
+	spin_lock(&sbinfo->stat_lock);
+	if (sbinfo->max_blocks) {
 		buf->f_blocks = sbinfo->max_blocks;
 		buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
+	}
+	if (sbinfo->max_inodes) {
 		buf->f_files = sbinfo->max_inodes;
 		buf->f_ffree = sbinfo->free_inodes;
-		spin_unlock(&sbinfo->stat_lock);
 	}
 	/* else leave those fields 0 like simple_statfs */
+	spin_unlock(&sbinfo->stat_lock);
 	return 0;
 }
 
@@ -1672,7 +1649,7 @@ static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentr
 	 * but each new link needs a new dentry, pinning lowmem, and
 	 * tmpfs dentries cannot be pruned until they are unlinked.
 	 */
-	if (sbinfo) {
+	if (sbinfo->max_inodes) {
 		spin_lock(&sbinfo->stat_lock);
 		if (!sbinfo->free_inodes) {
 			spin_unlock(&sbinfo->stat_lock);
@@ -1697,7 +1674,7 @@ static int shmem_unlink(struct inode *dir, struct dentry *dentry)
 
 	if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) {
 		struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
-		if (sbinfo) {
+		if (sbinfo->max_inodes) {
 			spin_lock(&sbinfo->stat_lock);
 			sbinfo->free_inodes++;
 			spin_unlock(&sbinfo->stat_lock);
@@ -1921,22 +1898,42 @@ bad_val:
 static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
 {
 	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
-	unsigned long max_blocks = 0;
-	unsigned long max_inodes = 0;
+	unsigned long max_blocks = sbinfo->max_blocks;
+	unsigned long max_inodes = sbinfo->max_inodes;
+	unsigned long blocks;
+	unsigned long inodes;
+	int error = -EINVAL;
+
+	if (shmem_parse_options(data, NULL, NULL, NULL,
+				&max_blocks, &max_inodes))
+		return error;
 
-	if (sbinfo) {
-		max_blocks = sbinfo->max_blocks;
-		max_inodes = sbinfo->max_inodes;
-	}
-	if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks, &max_inodes))
-		return -EINVAL;
-	/* Keep it simple: disallow limited <-> unlimited remount */
-	if ((max_blocks || max_inodes) == !sbinfo)
-		return -EINVAL;
-	/* But allow the pointless unlimited -> unlimited remount */
-	if (!sbinfo)
-		return 0;
-	return shmem_set_size(sbinfo, max_blocks, max_inodes);
+	spin_lock(&sbinfo->stat_lock);
+	blocks = sbinfo->max_blocks - sbinfo->free_blocks;
+	inodes = sbinfo->max_inodes - sbinfo->free_inodes;
+	if (max_blocks < blocks)
+		goto out;
+	if (max_inodes < inodes)
+		goto out;
+	/*
+	 * Those tests also disallow limited->unlimited while any are in
+	 * use, so i_blocks will always be zero when max_blocks is zero;
+	 * but we must separately disallow unlimited->limited, because
+	 * in that case we have no record of how much is already in use.
+	 */
+	if (max_blocks && !sbinfo->max_blocks)
+		goto out;
+	if (max_inodes && !sbinfo->max_inodes)
+		goto out;
+
+	error = 0;
+	sbinfo->max_blocks  = max_blocks;
+	sbinfo->free_blocks = max_blocks - blocks;
+	sbinfo->max_inodes  = max_inodes;
+	sbinfo->free_inodes = max_inodes - inodes;
+out:
+	spin_unlock(&sbinfo->stat_lock);
+	return error;
 }
 #endif
 
@@ -1961,11 +1958,11 @@ static int shmem_fill_super(struct super_block *sb,
 	uid_t uid = current->fsuid;
 	gid_t gid = current->fsgid;
 	int err = -ENOMEM;
-
-#ifdef CONFIG_TMPFS
+	struct shmem_sb_info *sbinfo;
 	unsigned long blocks = 0;
 	unsigned long inodes = 0;
 
+#ifdef CONFIG_TMPFS
 	/*
 	 * Per default we only allow half of the physical ram per
 	 * tmpfs instance, limiting inodes to one per page of lowmem;
@@ -1976,34 +1973,34 @@ static int shmem_fill_super(struct super_block *sb,
 		inodes = totalram_pages - totalhigh_pages;
 		if (inodes > blocks)
 			inodes = blocks;
-
-		if (shmem_parse_options(data, &mode,
-					&uid, &gid, &blocks, &inodes))
+		if (shmem_parse_options(data, &mode, &uid, &gid,
+					&blocks, &inodes))
 			return -EINVAL;
 	}
-
-	if (blocks || inodes) {
-		struct shmem_sb_info *sbinfo;
-		sbinfo = kmalloc(sizeof(struct shmem_sb_info), GFP_KERNEL);
-		if (!sbinfo)
-			return -ENOMEM;
-		sb->s_fs_info = sbinfo;
-		spin_lock_init(&sbinfo->stat_lock);
-		sbinfo->max_blocks = blocks;
-		sbinfo->free_blocks = blocks;
-		sbinfo->max_inodes = inodes;
-		sbinfo->free_inodes = inodes;
-	}
-	sb->s_xattr = shmem_xattr_handlers;
 #else
 	sb->s_flags |= MS_NOUSER;
 #endif
 
+	/* Round up to L1_CACHE_BYTES to resist false sharing */
+	sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info),
+				L1_CACHE_BYTES), GFP_KERNEL);
+	if (!sbinfo)
+		return -ENOMEM;
+
+	spin_lock_init(&sbinfo->stat_lock);
+	sbinfo->max_blocks = blocks;
+	sbinfo->free_blocks = blocks;
+	sbinfo->max_inodes = inodes;
+	sbinfo->free_inodes = inodes;
+
+	sb->s_fs_info = sbinfo;
 	sb->s_maxbytes = SHMEM_MAX_BYTES;
 	sb->s_blocksize = PAGE_CACHE_SIZE;
 	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 	sb->s_magic = TMPFS_MAGIC;
 	sb->s_op = &shmem_ops;
+	sb->s_xattr = shmem_xattr_handlers;
+
 	inode = shmem_get_inode(sb, S_IFDIR | mode, 0);
 	if (!inode)
 		goto failed;