create-proc-ext4-stats-file-more-carefully

   1 ext4: fix #11321: create /proc/ext4/*/stats more carefully
   2
   3 From: Alexey Dobriyan <adobriyan@gmail.com>
   4
   5 ext4 creates per-suberblock directory in /proc/ext4/ . Name used as
   6 basis is taken from bdevname, which, surprise, can contain slash.
   7
   8 However, proc while allowing to use proc_create("a/b", parent) form of
   9 PDE creation, assumes that parent/a was already created.
  10
  11 bdevname in question is 'cciss/c0d0p9', directory is not created and all
  12 this stuff goes directly into /proc (which is real bug).
  13
  14 Warning comes when _second_ partition is mounted.
  15
  16 http://bugzilla.kernel.org/show_bug.cgi?id=11321
  17
  18 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
  19 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
  20 diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
  21 index 2721643..78d628b 100644
  22 --- a/fs/ext4/mballoc.c
  23 +++ b/fs/ext4/mballoc.c
  24 @@ -2785,14 +2785,20 @@ static int ext4_mb_init_per_dev_proc(struct super_block *sb)
  25         mode_t mode = S_IFREG | S_IRUGO | S_IWUSR;
  26         struct ext4_sb_info *sbi = EXT4_SB(sb);
  27         struct proc_dir_entry *proc;
  28 -       char devname[64];
  29 +       char devname[64], *p;
  30
  31         if (proc_root_ext4 == NULL) {
  32                 sbi->s_mb_proc = NULL;
  33                 return -EINVAL;
  34         }
  35         bdevname(sb->s_bdev, devname);
  36 +       p = devname;
  37 +       while ((p = strchr(p, '/')))
  38 +               *p = '!';
  39 +
  40         sbi->s_mb_proc = proc_mkdir(devname, proc_root_ext4);
  41 +       if (!sbi->s_mb_proc)
  42 +               goto err_create_dir;
  43
  44         MB_PROC_HANDLER(EXT4_MB_STATS_NAME, stats);
  45         MB_PROC_HANDLER(EXT4_MB_MAX_TO_SCAN_NAME, max_to_scan);
  46 @@ -2804,7 +2810,6 @@ static int ext4_mb_init_per_dev_proc(struct super_block *sb)
  47         return 0;
  48
  49  err_out:
  50 -       printk(KERN_ERR "EXT4-fs: Unable to create %s\n", devname);
  51         remove_proc_entry(EXT4_MB_GROUP_PREALLOC, sbi->s_mb_proc);
  52         remove_proc_entry(EXT4_MB_STREAM_REQ, sbi->s_mb_proc);
  53         remove_proc_entry(EXT4_MB_ORDER2_REQ, sbi->s_mb_proc);
  54 @@ -2813,6 +2818,8 @@ err_out:
  55         remove_proc_entry(EXT4_MB_STATS_NAME, sbi->s_mb_proc);
  56         remove_proc_entry(devname, proc_root_ext4);
  57         sbi->s_mb_proc = NULL;
  58 +err_create_dir:
  59 +       printk(KERN_ERR "EXT4-fs: Unable to create %s\n", devname);
  60
  61         return -ENOMEM;
  62  }