nilfs2: replace BUG_ON and BUG calls triggerable from ioctl

Pekka Enberg advised me:
> It would be nice if BUG(), BUG_ON(), and panic() calls would be
> converted to proper error handling using WARN_ON() calls. The BUG()
> call in nilfs_cpfile_delete_checkpoints(), for example, looks to be
> triggerable from user-space via the ioctl() system call.

This will follow the comment and keep them to a minimum.

Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 21 insertions, 17 deletions

diff --git a/fs/nilfs2/cpfile.c b/fs/nilfs2/cpfile.c
index 218b34418508..e90b60dfced9 100644
--- a/fs/nilfs2/cpfile.c
+++ b/fs/nilfs2/cpfile.c
@@ -40,10 +40,7 @@ nilfs_cpfile_checkpoints_per_block(const struct inode *cpfile)
 static unsigned long
 nilfs_cpfile_get_blkoff(const struct inode *cpfile, __u64 cno)
 {
-        __u64 tcno;
-
-        BUG_ON(cno == 0); /* checkpoint number 0 is invalid */
-        tcno = cno + NILFS_MDT(cpfile)->mi_first_entry_offset - 1;
+        __u64 tcno = cno + NILFS_MDT(cpfile)->mi_first_entry_offset - 1;
         do_div(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
         return (unsigned long)tcno;
 }
@@ -96,7 +93,7 @@ nilfs_cpfile_block_sub_valid_checkpoints(const struct inode *cpfile,
         struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
         unsigned int count;
 
-        BUG_ON(le32_to_cpu(cp->cp_checkpoints_count) < n);
+        WARN_ON(le32_to_cpu(cp->cp_checkpoints_count) < n);
         count = le32_to_cpu(cp->cp_checkpoints_count) - n;
         cp->cp_checkpoints_count = cpu_to_le32(count);
         return count;
@@ -178,6 +175,8 @@ static inline int nilfs_cpfile_delete_checkpoint_block(struct inode *cpfile,
  * %-ENOMEM - Insufficient amount of memory available.
  *
  * %-ENOENT - No such checkpoint.
+ *
+ * %-EINVAL - invalid checkpoint.
  */
 int nilfs_cpfile_get_checkpoint(struct inode *cpfile,
                                 __u64 cno,
@@ -191,8 +190,9 @@ int nilfs_cpfile_get_checkpoint(struct inode *cpfile,
         void *kaddr;
         int ret;
 
-        BUG_ON(cno < 1 || cno > nilfs_mdt_cno(cpfile) ||
-               (cno < nilfs_mdt_cno(cpfile) && create));
+        if (unlikely(cno < 1 || cno > nilfs_mdt_cno(cpfile) ||
+                     (cno < nilfs_mdt_cno(cpfile) && create)))
+                return -EINVAL;
 
         down_write(&NILFS_MDT(cpfile)->mi_sem);
 
@@ -288,12 +288,11 @@ int nilfs_cpfile_delete_checkpoints(struct inode *cpfile,
         unsigned long tnicps;
         int ret, ncps, nicps, count, i;
 
-        if ((start == 0) || (start > end)) {
-                printk(KERN_CRIT "%s: start = %llu, end = %llu\n",
-                       __func__,
-                       (unsigned long long)start,
-                       (unsigned long long)end);
-                BUG();
+        if (unlikely(start == 0 || start > end)) {
+                printk(KERN_ERR "%s: invalid range of checkpoint numbers: "
+                       "[%llu, %llu)\n", __func__,
+                       (unsigned long long)start, (unsigned long long)end);
+                return -EINVAL;
         }
 
         /* cannot delete the latest checkpoint */
@@ -323,7 +322,7 @@ int nilfs_cpfile_delete_checkpoints(struct inode *cpfile,
                         cpfile, cno, cp_bh, kaddr);
                 nicps = 0;
                 for (i = 0; i < ncps; i++, cp = (void *)cp + cpsz) {
-                        BUG_ON(nilfs_checkpoint_snapshot(cp));
+                        WARN_ON(nilfs_checkpoint_snapshot(cp));
                         if (!nilfs_checkpoint_invalid(cp)) {
                                 nilfs_checkpoint_set_invalid(cp);
                                 nicps++;
@@ -393,6 +392,8 @@ static ssize_t nilfs_cpfile_do_get_cpinfo(struct inode *cpfile, __u64 *cnop,
         int n, ret;
         int ncps, i;
 
+        if (cno == 0)
+                return -ENOENT; /* checkpoint number 0 is invalid */
         down_read(&NILFS_MDT(cpfile)->mi_sem);
 
         for (n = 0; cno < cur_cno && n < nci; cno += ncps) {
@@ -532,9 +533,6 @@ int nilfs_cpfile_delete_checkpoint(struct inode *cpfile, __u64 cno)
         ssize_t nci;
         int ret;
 
-        /* checkpoint number 0 is invalid */
-        if (cno == 0)
-                return -ENOENT;
         nci = nilfs_cpfile_do_get_cpinfo(cpfile, &tcno, &ci, 1);
         if (nci < 0)
                 return nci;
@@ -582,6 +580,8 @@ static int nilfs_cpfile_set_snapshot(struct inode *cpfile, __u64 cno)
         void *kaddr;
         int ret;
 
+        if (cno == 0)
+                return -ENOENT; /* checkpoint number 0 is invalid */
         down_write(&NILFS_MDT(cpfile)->mi_sem);
 
         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
@@ -698,6 +698,8 @@ static int nilfs_cpfile_clear_snapshot(struct inode *cpfile, __u64 cno)
         void *kaddr;
         int ret;
 
+        if (cno == 0)
+                return -ENOENT; /* checkpoint number 0 is invalid */
         down_write(&NILFS_MDT(cpfile)->mi_sem);
 
         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
@@ -813,6 +815,8 @@ int nilfs_cpfile_is_snapshot(struct inode *cpfile, __u64 cno)
         void *kaddr;
         int ret;
 
+        if (cno == 0)
+                return -ENOENT; /* checkpoint number 0 is invalid */
         down_read(&NILFS_MDT(cpfile)->mi_sem);
 
         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &bh);