vfs: check i_nlink limits in vfs_{mkdir,rename_dir,link}

New field of struct super_block - ->s_max_links. Maximal allowed value of ->i_nlink or 0; in the latter case all checks still need to be done in ->link/->mkdir/->rename instances. Note that this limit applies both to directoris and to non-directories. Signed-off-by: Al Viro <[email protected]>
kyagi · Mar 21, 2012 · 8de5277 · 8de5277
1 parent c16fa4f
commit 8de5277
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Showing 26 changed files with 46 additions and 149 deletions.
diff --git a/fs/exofs/namei.c b/fs/exofs/namei.c
@@ -143,9 +143,6 @@ static int exofs_link(struct dentry *old_dentry, struct inode *dir,
 {
 	struct inode *inode = old_dentry->d_inode;
 
-	if (inode->i_nlink >= EXOFS_LINK_MAX)
-		return -EMLINK;
-
 	inode->i_ctime = CURRENT_TIME;
 	inode_inc_link_count(inode);
 	ihold(inode);
@@ -156,10 +153,7 @@ static int exofs_link(struct dentry *old_dentry, struct inode *dir,
 static int exofs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 {
 	struct inode *inode;
-	int err = -EMLINK;
-
-	if (dir->i_nlink >= EXOFS_LINK_MAX)
-		goto out;
+	int err;
 
 	inode_inc_link_count(dir);
 
@@ -275,11 +269,6 @@ static int exofs_rename(struct inode *old_dir, struct dentry *old_dentry,
 		if (err)
 			goto out_dir;
 	} else {
-		if (dir_de) {
-			err = -EMLINK;
-			if (new_dir->i_nlink >= EXOFS_LINK_MAX)
-				goto out_dir;
-		}
 		err = exofs_add_link(new_dentry, old_inode);
 		if (err)
 			goto out_dir;

diff --git a/fs/exofs/super.c b/fs/exofs/super.c
@@ -754,6 +754,7 @@ static int exofs_fill_super(struct super_block *sb, void *data, int silent)
 	sb->s_blocksize = EXOFS_BLKSIZE;
 	sb->s_blocksize_bits = EXOFS_BLKSHIFT;
 	sb->s_maxbytes = MAX_LFS_FILESIZE;
+	sb->s_max_links = EXOFS_LINK_MAX;
 	atomic_set(&sbi->s_curr_pending, 0);
 	sb->s_bdev = NULL;
 	sb->s_dev = 0;

diff --git a/fs/ext2/namei.c b/fs/ext2/namei.c
@@ -195,9 +195,6 @@ static int ext2_link (struct dentry * old_dentry, struct inode * dir,
 	struct inode *inode = old_dentry->d_inode;
 	int err;
 
-	if (inode->i_nlink >= EXT2_LINK_MAX)
-		return -EMLINK;
-
 	dquot_initialize(dir);
 
 	inode->i_ctime = CURRENT_TIME_SEC;
@@ -217,10 +214,7 @@ static int ext2_link (struct dentry * old_dentry, struct inode * dir,
 static int ext2_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode)
 {
 	struct inode * inode;
-	int err = -EMLINK;
-
-	if (dir->i_nlink >= EXT2_LINK_MAX)
-		goto out;
+	int err;
 
 	dquot_initialize(dir);
 
@@ -346,11 +340,6 @@ static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
 			drop_nlink(new_inode);
 		inode_dec_link_count(new_inode);
 	} else {
-		if (dir_de) {
-			err = -EMLINK;
-			if (new_dir->i_nlink >= EXT2_LINK_MAX)
-				goto out_dir;
-		}
 		err = ext2_add_link(new_dentry, old_inode);
 		if (err)
 			goto out_dir;

diff --git a/fs/ext2/super.c b/fs/ext2/super.c
@@ -919,6 +919,7 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
 	}
 
 	sb->s_maxbytes = ext2_max_size(sb->s_blocksize_bits);
+	sb->s_max_links = EXT2_LINK_MAX;
 
 	if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV) {
 		sbi->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;

diff --git a/fs/jfs/namei.c b/fs/jfs/namei.c
@@ -220,12 +220,6 @@ static int jfs_mkdir(struct inode *dip, struct dentry *dentry, umode_t mode)
 
 	dquot_initialize(dip);
 
-	/* link count overflow on parent directory ? */
-	if (dip->i_nlink == JFS_LINK_MAX) {
-		rc = -EMLINK;
-		goto out1;
-	}
-
 	/*
 	 * search parent directory for entry/freespace
 	 * (dtSearch() returns parent directory page pinned)
@@ -806,9 +800,6 @@ static int jfs_link(struct dentry *old_dentry,
 	jfs_info("jfs_link: %s %s", old_dentry->d_name.name,
 		 dentry->d_name.name);
 
-	if (ip->i_nlink == JFS_LINK_MAX)
-		return -EMLINK;
-
 	dquot_initialize(dir);
 
 	tid = txBegin(ip->i_sb, 0);
@@ -1138,10 +1129,6 @@ static int jfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 				rc = -ENOTEMPTY;
 				goto out3;
 			}
-		} else if ((new_dir != old_dir) &&
-			   (new_dir->i_nlink == JFS_LINK_MAX)) {
-			rc = -EMLINK;
-			goto out3;
 		}
 	} else if (new_ip) {
 		IWRITE_LOCK(new_ip, RDWRLOCK_NORMAL);

diff --git a/fs/jfs/super.c b/fs/jfs/super.c
@@ -441,6 +441,7 @@ static int jfs_fill_super(struct super_block *sb, void *data, int silent)
 		return -ENOMEM;
 
 	sb->s_fs_info = sbi;
+	sb->s_max_links = JFS_LINK_MAX;
 	sbi->sb = sb;
 	sbi->uid = sbi->gid = sbi->umask = -1;
 

diff --git a/fs/logfs/dir.c b/fs/logfs/dir.c
@@ -558,9 +558,6 @@ static int logfs_link(struct dentry *old_dentry, struct inode *dir,
 {
 	struct inode *inode = old_dentry->d_inode;
 
-	if (inode->i_nlink >= LOGFS_LINK_MAX)
-		return -EMLINK;
-
 	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 	ihold(inode);
 	inc_nlink(inode);

diff --git a/fs/logfs/super.c b/fs/logfs/super.c
@@ -542,6 +542,7 @@ static struct dentry *logfs_get_sb_device(struct logfs_super *super,
 	 * the filesystem incompatible with 32bit systems.
 	 */
 	sb->s_maxbytes	= (1ull << 43) - 1;
+	sb->s_max_links = LOGFS_LINK_MAX;
 	sb->s_op	= &logfs_super_operations;
 	sb->s_flags	= flags | MS_NOATIME;
 

diff --git a/fs/minix/inode.c b/fs/minix/inode.c
@@ -190,24 +190,24 @@ static int minix_fill_super(struct super_block *s, void *data, int silent)
 		sbi->s_version = MINIX_V1;
 		sbi->s_dirsize = 16;
 		sbi->s_namelen = 14;
-		sbi->s_link_max = MINIX_LINK_MAX;
+		s->s_max_links = MINIX_LINK_MAX;
 	} else if (s->s_magic == MINIX_SUPER_MAGIC2) {
 		sbi->s_version = MINIX_V1;
 		sbi->s_dirsize = 32;
 		sbi->s_namelen = 30;
-		sbi->s_link_max = MINIX_LINK_MAX;
+		s->s_max_links = MINIX_LINK_MAX;
 	} else if (s->s_magic == MINIX2_SUPER_MAGIC) {
 		sbi->s_version = MINIX_V2;
 		sbi->s_nzones = ms->s_zones;
 		sbi->s_dirsize = 16;
 		sbi->s_namelen = 14;
-		sbi->s_link_max = MINIX2_LINK_MAX;
+		s->s_max_links = MINIX2_LINK_MAX;
 	} else if (s->s_magic == MINIX2_SUPER_MAGIC2) {
 		sbi->s_version = MINIX_V2;
 		sbi->s_nzones = ms->s_zones;
 		sbi->s_dirsize = 32;
 		sbi->s_namelen = 30;
-		sbi->s_link_max = MINIX2_LINK_MAX;
+		s->s_max_links = MINIX2_LINK_MAX;
 	} else if ( *(__u16 *)(bh->b_data + 24) == MINIX3_SUPER_MAGIC) {
 		m3s = (struct minix3_super_block *) bh->b_data;
 		s->s_magic = m3s->s_magic;
@@ -221,9 +221,9 @@ static int minix_fill_super(struct super_block *s, void *data, int silent)
 		sbi->s_dirsize = 64;
 		sbi->s_namelen = 60;
 		sbi->s_version = MINIX_V3;
-		sbi->s_link_max = MINIX2_LINK_MAX;
 		sbi->s_mount_state = MINIX_VALID_FS;
 		sb_set_blocksize(s, m3s->s_blocksize);
+		s->s_max_links = MINIX2_LINK_MAX;
 	} else
 		goto out_no_fs;
 

diff --git a/fs/minix/minix.h b/fs/minix/minix.h
@@ -34,7 +34,6 @@ struct minix_sb_info {
 	unsigned long s_max_size;
 	int s_dirsize;
 	int s_namelen;
-	int s_link_max;
 	struct buffer_head ** s_imap;
 	struct buffer_head ** s_zmap;
 	struct buffer_head * s_sbh;

diff --git a/fs/minix/namei.c b/fs/minix/namei.c
@@ -94,9 +94,6 @@ static int minix_link(struct dentry * old_dentry, struct inode * dir,
 {
 	struct inode *inode = old_dentry->d_inode;
 
-	if (inode->i_nlink >= minix_sb(inode->i_sb)->s_link_max)
-		return -EMLINK;
-
 	inode->i_ctime = CURRENT_TIME_SEC;
 	inode_inc_link_count(inode);
 	ihold(inode);
@@ -106,10 +103,7 @@ static int minix_link(struct dentry * old_dentry, struct inode * dir,
 static int minix_mkdir(struct inode * dir, struct dentry *dentry, umode_t mode)
 {
 	struct inode * inode;
-	int err = -EMLINK;
-
-	if (dir->i_nlink >= minix_sb(dir->i_sb)->s_link_max)
-		goto out;
+	int err;
 
 	inode_inc_link_count(dir);
 
@@ -181,7 +175,6 @@ static int minix_rmdir(struct inode * dir, struct dentry *dentry)
 static int minix_rename(struct inode * old_dir, struct dentry *old_dentry,
 			   struct inode * new_dir, struct dentry *new_dentry)
 {
-	struct minix_sb_info * info = minix_sb(old_dir->i_sb);
 	struct inode * old_inode = old_dentry->d_inode;
 	struct inode * new_inode = new_dentry->d_inode;
 	struct page * dir_page = NULL;
@@ -219,11 +212,6 @@ static int minix_rename(struct inode * old_dir, struct dentry *old_dentry,
 			drop_nlink(new_inode);
 		inode_dec_link_count(new_inode);
 	} else {
-		if (dir_de) {
-			err = -EMLINK;
-			if (new_dir->i_nlink >= info->s_link_max)
-				goto out_dir;
-		}
 		err = minix_add_link(new_dentry, old_inode);
 		if (err)
 			goto out_dir;

diff --git a/fs/namei.c b/fs/namei.c
@@ -2569,6 +2569,7 @@ SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, d
 int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 {
 	int error = may_create(dir, dentry);
+	unsigned max_links = dir->i_sb->s_max_links;
 
 	if (error)
 		return error;
@@ -2581,6 +2582,9 @@ int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 	if (error)
 		return error;
 
+	if (max_links && dir->i_nlink >= max_links)
+		return -EMLINK;
+
 	error = dir->i_op->mkdir(dir, dentry, mode);
 	if (!error)
 		fsnotify_mkdir(dir, dentry);
@@ -2911,6 +2915,7 @@ SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newn
 int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
 {
 	struct inode *inode = old_dentry->d_inode;
+	unsigned max_links = dir->i_sb->s_max_links;
 	int error;
 
 	if (!inode)
@@ -2941,6 +2946,8 @@ int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_de
 	/* Make sure we don't allow creating hardlink to an unlinked file */
 	if (inode->i_nlink == 0)
 		error =  -ENOENT;
+	else if (max_links && inode->i_nlink >= max_links)
+		error = -EMLINK;
 	else
 		error = dir->i_op->link(old_dentry, dir, new_dentry);
 	mutex_unlock(&inode->i_mutex);
@@ -3050,6 +3057,7 @@ static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
 {
 	int error = 0;
 	struct inode *target = new_dentry->d_inode;
+	unsigned max_links = new_dir->i_sb->s_max_links;
 
 	/*
 	 * If we are going to change the parent - check write permissions,
@@ -3073,6 +3081,11 @@ static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
 	if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry))
 		goto out;
 
+	error = -EMLINK;
+	if (max_links && !target && new_dir != old_dir &&
+	    new_dir->i_nlink >= max_links)
+		goto out;
+
 	if (target)
 		shrink_dcache_parent(new_dentry);
 	error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);

diff --git a/fs/nilfs2/namei.c b/fs/nilfs2/namei.c
@@ -193,9 +193,6 @@ static int nilfs_link(struct dentry *old_dentry, struct inode *dir,
 	struct nilfs_transaction_info ti;
 	int err;
 
-	if (inode->i_nlink >= NILFS_LINK_MAX)
-		return -EMLINK;
-
 	err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
 	if (err)
 		return err;
@@ -219,9 +216,6 @@ static int nilfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 	struct nilfs_transaction_info ti;
 	int err;
 
-	if (dir->i_nlink >= NILFS_LINK_MAX)
-		return -EMLINK;
-
 	err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
 	if (err)
 		return err;
@@ -400,11 +394,6 @@ static int nilfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 		drop_nlink(new_inode);
 		nilfs_mark_inode_dirty(new_inode);
 	} else {
-		if (dir_de) {
-			err = -EMLINK;
-			if (new_dir->i_nlink >= NILFS_LINK_MAX)
-				goto out_dir;
-		}
 		err = nilfs_add_link(new_dentry, old_inode);
 		if (err)
 			goto out_dir;

diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
@@ -1059,6 +1059,7 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent)
 	sb->s_export_op = &nilfs_export_ops;
 	sb->s_root = NULL;
 	sb->s_time_gran = 1;
+	sb->s_max_links = NILFS_LINK_MAX;
 
 	bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
 	sb->s_bdi = bdi ? : &default_backing_dev_info;

diff --git a/fs/sysv/namei.c b/fs/sysv/namei.c
@@ -121,9 +121,6 @@ static int sysv_link(struct dentry * old_dentry, struct inode * dir,
 {
 	struct inode *inode = old_dentry->d_inode;
 
-	if (inode->i_nlink >= SYSV_SB(inode->i_sb)->s_link_max)
-		return -EMLINK;
-
 	inode->i_ctime = CURRENT_TIME_SEC;
 	inode_inc_link_count(inode);
 	ihold(inode);
@@ -134,10 +131,8 @@ static int sysv_link(struct dentry * old_dentry, struct inode * dir,
 static int sysv_mkdir(struct inode * dir, struct dentry *dentry, umode_t mode)
 {
 	struct inode * inode;
-	int err = -EMLINK;
+	int err;
 
-	if (dir->i_nlink >= SYSV_SB(dir->i_sb)->s_link_max) 
-		goto out;
 	inode_inc_link_count(dir);
 
 	inode = sysv_new_inode(dir, S_IFDIR|mode);
@@ -251,11 +246,6 @@ static int sysv_rename(struct inode * old_dir, struct dentry * old_dentry,
 			drop_nlink(new_inode);
 		inode_dec_link_count(new_inode);
 	} else {
-		if (dir_de) {
-			err = -EMLINK;
-			if (new_dir->i_nlink >= SYSV_SB(new_dir->i_sb)->s_link_max)
-				goto out_dir;
-		}
 		err = sysv_add_link(new_dentry, old_inode);
 		if (err)
 			goto out_dir;