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, 13 insertions, 24 deletions

diff --git a/fs/sysv/namei.c b/fs/sysv/namei.c
index b217797e621b..d7466e293614 100644
--- 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;
diff --git a/fs/sysv/super.c b/fs/sysv/super.c
index f60c196913ea..f467740e088c 100644
--- a/fs/sysv/super.c
+++ b/fs/sysv/super.c
@@ -44,7 +44,7 @@ enum {
         JAN_1_1980 = (10*365 + 2) * 24 * 60 * 60
 };
 
-static void detected_xenix(struct sysv_sb_info *sbi)
+static void detected_xenix(struct sysv_sb_info *sbi, unsigned *max_links)
 {
         struct buffer_head *bh1 = sbi->s_bh1;
         struct buffer_head *bh2 = sbi->s_bh2;
@@ -59,7 +59,7 @@ static void detected_xenix(struct sysv_sb_info *sbi)
                 sbd2 = (struct xenix_super_block *) (bh2->b_data - 512);
         }
 
-        sbi->s_link_max = XENIX_LINK_MAX;
+        *max_links = XENIX_LINK_MAX;
         sbi->s_fic_size = XENIX_NICINOD;
         sbi->s_flc_size = XENIX_NICFREE;
         sbi->s_sbd1 = (char *)sbd1;
@@ -75,7 +75,7 @@ static void detected_xenix(struct sysv_sb_info *sbi)
         sbi->s_nzones = fs32_to_cpu(sbi, sbd1->s_fsize);
 }
 
-static void detected_sysv4(struct sysv_sb_info *sbi)
+static void detected_sysv4(struct sysv_sb_info *sbi, unsigned *max_links)
 {
         struct sysv4_super_block * sbd;
         struct buffer_head *bh1 = sbi->s_bh1;
@@ -86,7 +86,7 @@ static void detected_sysv4(struct sysv_sb_info *sbi)
         else
                 sbd = (struct sysv4_super_block *) bh2->b_data;
 
-        sbi->s_link_max = SYSV_LINK_MAX;
+        *max_links = SYSV_LINK_MAX;
         sbi->s_fic_size = SYSV_NICINOD;
         sbi->s_flc_size = SYSV_NICFREE;
         sbi->s_sbd1 = (char *)sbd;
@@ -103,7 +103,7 @@ static void detected_sysv4(struct sysv_sb_info *sbi)
         sbi->s_nzones = fs32_to_cpu(sbi, sbd->s_fsize);
 }
 
-static void detected_sysv2(struct sysv_sb_info *sbi)
+static void detected_sysv2(struct sysv_sb_info *sbi, unsigned *max_links)
 {
         struct sysv2_super_block *sbd;
         struct buffer_head *bh1 = sbi->s_bh1;
@@ -114,7 +114,7 @@ static void detected_sysv2(struct sysv_sb_info *sbi)
         else
                 sbd = (struct sysv2_super_block *) bh2->b_data;
 
-        sbi->s_link_max = SYSV_LINK_MAX;
+        *max_links = SYSV_LINK_MAX;
         sbi->s_fic_size = SYSV_NICINOD;
         sbi->s_flc_size = SYSV_NICFREE;
         sbi->s_sbd1 = (char *)sbd;
@@ -131,14 +131,14 @@ static void detected_sysv2(struct sysv_sb_info *sbi)
         sbi->s_nzones = fs32_to_cpu(sbi, sbd->s_fsize);
 }
 
-static void detected_coherent(struct sysv_sb_info *sbi)
+static void detected_coherent(struct sysv_sb_info *sbi, unsigned *max_links)
 {
         struct coh_super_block * sbd;
         struct buffer_head *bh1 = sbi->s_bh1;
 
         sbd = (struct coh_super_block *) bh1->b_data;
 
-        sbi->s_link_max = COH_LINK_MAX;
+        *max_links = COH_LINK_MAX;
         sbi->s_fic_size = COH_NICINOD;
         sbi->s_flc_size = COH_NICFREE;
         sbi->s_sbd1 = (char *)sbd;
@@ -154,12 +154,12 @@ static void detected_coherent(struct sysv_sb_info *sbi)
         sbi->s_nzones = fs32_to_cpu(sbi, sbd->s_fsize);
 }
 
-static void detected_v7(struct sysv_sb_info *sbi)
+static void detected_v7(struct sysv_sb_info *sbi, unsigned *max_links)
 {
         struct buffer_head *bh2 = sbi->s_bh2;
         struct v7_super_block *sbd = (struct v7_super_block *)bh2->b_data;
 
-        sbi->s_link_max = V7_LINK_MAX;
+        *max_links = V7_LINK_MAX;
         sbi->s_fic_size = V7_NICINOD;
         sbi->s_flc_size = V7_NICFREE;
         sbi->s_sbd1 = (char *)sbd;
@@ -290,7 +290,7 @@ static char *flavour_names[] = {
         [FSTYPE_AFS]    = "AFS",
 };
 
-static void (*flavour_setup[])(struct sysv_sb_info *) = {
+static void (*flavour_setup[])(struct sysv_sb_info *, unsigned *) = {
         [FSTYPE_XENIX]  = detected_xenix,
         [FSTYPE_SYSV4]  = detected_sysv4,
         [FSTYPE_SYSV2]  = detected_sysv2,
@@ -310,7 +310,7 @@ static int complete_read_super(struct super_block *sb, int silent, int size)
 
         sbi->s_firstinodezone = 2;
 
-        flavour_setup[sbi->s_type](sbi);
+        flavour_setup[sbi->s_type](sbi, &sb->s_max_links);
         
         sbi->s_truncate = 1;
         sbi->s_ndatazones = sbi->s_nzones - sbi->s_firstdatazone;
diff --git a/fs/sysv/sysv.h b/fs/sysv/sysv.h
index 0e4b821c5691..11b07672f6c5 100644
--- a/fs/sysv/sysv.h
+++ b/fs/sysv/sysv.h
@@ -24,7 +24,6 @@ struct sysv_sb_info {
         char           s_bytesex;       /* bytesex (le/be/pdp) */
         char           s_truncate;      /* if 1: names > SYSV_NAMELEN chars are truncated */
                                         /* if 0: they are disallowed (ENAMETOOLONG) */
-        nlink_t        s_link_max;      /* max number of hard links to a file */
         unsigned int   s_inodes_per_block;      /* number of inodes per block */
         unsigned int   s_inodes_per_block_1;    /* inodes_per_block - 1 */
         unsigned int   s_inodes_per_block_bits; /* log2(inodes_per_block) */