initialize-multi-block-allocator-before-checking-block-descriptors

   1 ext4: initialize multi-block allocator before checking block descriptors
   2
   3 From:   Azat Khuzhin <a3at.mail@gmail.com>
   4
   5 With EXT4FS_DEBUG ext4_count_free_clusters() will call
   6 ext4_read_block_bitmap() without s_group_info initialized, so we need to
   7 initialize multi-block allocator before.
   8
   9 And dependencies that must be solved, to allow this:
  10 - multi-block allocator needs in group descriptors
  11 - need to install s_op before initializing multi-block allocator,
  12   because in ext4_mb_init_backend() new inode is created.
  13 - initialize number of group desc blocks (s_gdb_count) otherwise
  14   number of clusters returned by ext4_free_clusters_after_init() is not correct.
  15   (see ext4_bg_num_gdb_nometa())
  16
  17 Here is the stack backtrace:
  18
  19 (gdb) bt
  20  #0  ext4_get_group_info (group=0, sb=0xffff880079a10000) at ext4.h:2430
  21  #1  ext4_validate_block_bitmap (sb=sb@entry=0xffff880079a10000,
  22      desc=desc@entry=0xffff880056510000, block_group=block_group@entry=0,
  23      bh=bh@entry=0xffff88007bf2b2d8) at balloc.c:358
  24  #2  0xffffffff81232202 in ext4_wait_block_bitmap (sb=sb@entry=0xffff880079a10000,
  25      block_group=block_group@entry=0,
  26      bh=bh@entry=0xffff88007bf2b2d8) at balloc.c:476
  27  #3  0xffffffff81232eaf in ext4_read_block_bitmap (sb=sb@entry=0xffff880079a10000,
  28      block_group=block_group@entry=0) at balloc.c:489
  29  #4  0xffffffff81232fc0 in ext4_count_free_clusters (sb=sb@entry=0xffff880079a10000) at balloc.c:665
  30  #5  0xffffffff81259ffa in ext4_check_descriptors (first_not_zeroed=<synthetic pointer>,
  31      sb=0xffff880079a10000) at super.c:2143
  32  #6  ext4_fill_super (sb=sb@entry=0xffff880079a10000, data=<optimized out>,
  33      data@entry=0x0 <irq_stack_union>, silent=silent@entry=0) at super.c:3851
  34      ...
  35
  36 Signed-off-by: Azat Khuzhin <a3at.mail@gmail.com>
  37 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
  38 ---
  39 Link: http://marc.info/?l=linux-ext4&m=139493754530149&w=2
  40 v5: initialize number of group desc blocks (s_gdb_count) otherwise
  41     number of clusters returned by ext4_free_clusters_after_init() is not correct.
  42
  43  fs/ext4/super.c | 51 +++++++++++++++++++++++++++------------------------
  44  1 file changed, 27 insertions(+), 24 deletions(-)
  45
  46 diff --git a/fs/ext4/super.c b/fs/ext4/super.c
  47 index f3c6670..6f9e6fa 100644
  48 --- a/fs/ext4/super.c
  49 +++ b/fs/ext4/super.c
  50 @@ -3869,19 +3869,38 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
  51                         goto failed_mount2;
  52                 }
  53         }
  54 +
  55 +       /*
  56 +        * set up enough so that it can read an inode,
  57 +        * and create new inode for buddy allocator
  58 +        */
  59 +       sbi->s_gdb_count = db_count;
  60 +       if (!test_opt(sb, NOLOAD) &&
  61 +           EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_HAS_JOURNAL))
  62 +               sb->s_op = &ext4_sops;
  63 +       else
  64 +               sb->s_op = &ext4_nojournal_sops;
  65 +
  66 +       ext4_ext_init(sb);
  67 +       err = ext4_mb_init(sb);
  68 +       if (err) {
  69 +               ext4_msg(sb, KERN_ERR, "failed to initialize mballoc (%d)",
  70 +                        err);
  71 +               goto failed_mount2;
  72 +       }
  73 +
  74         if (!ext4_check_descriptors(sb, &first_not_zeroed)) {
  75                 ext4_msg(sb, KERN_ERR, "group descriptors corrupted!");
  76 -               goto failed_mount2;
  77 +               goto failed_mount2a;
  78         }
  79         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG))
  80                 if (!ext4_fill_flex_info(sb)) {
  81                         ext4_msg(sb, KERN_ERR,
  82                                "unable to initialize "
  83                                "flex_bg meta info!");
  84 -                       goto failed_mount2;
  85 +                       goto failed_mount2a;
  86                 }
  87
  88 -       sbi->s_gdb_count = db_count;
  89         get_random_bytes(&sbi->s_next_generation, sizeof(u32));
  90         spin_lock_init(&sbi->s_next_gen_lock);
  91
  92 @@ -3916,14 +3935,6 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
  93         sbi->s_stripe = ext4_get_stripe_size(sbi);
  94         sbi->s_extent_max_zeroout_kb = 32;
  95
  96 -       /*
  97 -        * set up enough so that it can read an inode
  98 -        */
  99 -       if (!test_opt(sb, NOLOAD) &&
 100 -           EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_HAS_JOURNAL))
 101 -               sb->s_op = &ext4_sops;
 102 -       else
 103 -               sb->s_op = &ext4_nojournal_sops;
 104         sb->s_export_op = &ext4_export_ops;
 105         sb->s_xattr = ext4_xattr_handlers;
 106  #ifdef CONFIG_QUOTA
 107 @@ -4113,21 +4124,13 @@ no_journal:
 108         if (err) {
 109                 ext4_msg(sb, KERN_ERR, "failed to reserve %llu clusters for "
 110                          "reserved pool", ext4_calculate_resv_clusters(sb));
 111 -               goto failed_mount4a;
 112 +               goto failed_mount5;
 113         }
 114
 115         err = ext4_setup_system_zone(sb);
 116         if (err) {
 117                 ext4_msg(sb, KERN_ERR, "failed to initialize system "
 118                          "zone (%d)", err);
 119 -               goto failed_mount4a;
 120 -       }
 121 -
 122 -       ext4_ext_init(sb);
 123 -       err = ext4_mb_init(sb);
 124 -       if (err) {
 125 -               ext4_msg(sb, KERN_ERR, "failed to initialize mballoc (%d)",
 126 -                        err);
 127                 goto failed_mount5;
 128         }
 129
 130 @@ -4204,11 +4207,8 @@ failed_mount8:
 131  failed_mount7:
 132         ext4_unregister_li_request(sb);
 133  failed_mount6:
 134 -       ext4_mb_release(sb);
 135 -failed_mount5:
 136 -       ext4_ext_release(sb);
 137         ext4_release_system_zone(sb);
 138 -failed_mount4a:
 139 +failed_mount5:
 140         dput(sb->s_root);
 141         sb->s_root = NULL;
 142  failed_mount4:
 143 @@ -4232,11 +4232,14 @@ failed_mount3:
 144         percpu_counter_destroy(&sbi->s_extent_cache_cnt);
 145         if (sbi->s_mmp_tsk)
 146                 kthread_stop(sbi->s_mmp_tsk);
 147 +failed_mount2a:
 148 +       ext4_mb_release(sb);
 149  failed_mount2:
 150         for (i = 0; i < db_count; i++)
 151                 brelse(sbi->s_group_desc[i]);
 152         ext4_kvfree(sbi->s_group_desc);
 153  failed_mount:
 154 +       ext4_ext_release(sb);
 155         if (sbi->s_chksum_driver)
 156                 crypto_free_shash(sbi->s_chksum_driver);
 157         if (sbi->s_proc) {
 158 --
 159 1.9.1
 160
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