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 <viro@zeniv.linux.org.uk>

3 files changed, 6 insertions, 19 deletions

diff --git a/fs/minix/inode.c b/fs/minix/inode.c
index fa8b612b8ce2..62c697caffb9 100644
--- 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
index c889ef0aa571..1ebd11854622 100644
--- 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
index 2f76e38c2065..2d0ee1786305 100644
--- 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;