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 we can't initialize multi-block allocator without group descriptors,
  10 since it use them.
  11 Also we need to install s_op before initializing multi-block allocator,
  12 because in ext4_mb_init_backend() new inode is created.
  13
  14 Here is bt:
  15 (gdb) bt
  16  #0  ext4_get_group_info (group=0, sb=0xffff880079a10000) at ext4.h:2430
  17  #1  ext4_validate_block_bitmap (sb=sb@entry=0xffff880079a10000, desc=desc@entry=0xffff880056510000, block_group=block_group@entry=0,
  18      bh=bh@entry=0xffff88007bf2b2d8) at balloc.c:358
  19  #2  0xffffffff81232202 in ext4_wait_block_bitmap (sb=sb@entry=0xffff880079a10000, block_group=block_group@entry=0,
  20      bh=bh@entry=0xffff88007bf2b2d8) at balloc.c:476
  21  #3  0xffffffff81232eaf in ext4_read_block_bitmap (sb=sb@entry=0xffff880079a10000, block_group=block_group@entry=0) at balloc.c:489
  22  #4  0xffffffff81232fc0 in ext4_count_free_clusters (sb=sb@entry=0xffff880079a10000) at balloc.c:665
  23  #5  0xffffffff81259ffa in ext4_check_descriptors (first_not_zeroed=<synthetic pointer>, sb=0xffff880079a10000) at super.c:2143
  24  #6  ext4_fill_super (sb=sb@entry=0xffff880079a10000, data=<optimized out>, data@entry=0x0 <irq_stack_union>, silent=silent@entry=0)
  25      at super.c:3851
  26  #7  0xffffffff811b8340 in mount_bdev (fs_type=<optimized out>, flags=0, dev_name=<optimized out>, data=0x0 <irq_stack_union>,
  27      fill_super=fill_super@entry=0xffffffff812589c0 <ext4_fill_super>) at super.c:987
  28  #8  0xffffffff8124ec35 in ext4_mount (fs_type=<optimized out>, flags=<optimized out>, dev_name=<optimized out>, data=<optimized out>)
  29      at super.c:5365
  30  #9  0xffffffff811b8cf9 in mount_fs (type=type@entry=0xffffffff81c71840 <ext4_fs_type>, flags=flags@entry=0,
  31      name=name@entry=0xffff880077a80c70 "/dev/loop4", data=data@entry=0x0 <irq_stack_union>) at super.c:1090
  32  #10 0xffffffff811d2ff3 in vfs_kern_mount (type=type@entry=0xffffffff81c71840 <ext4_fs_type>, flags=0,
  33      name=name@entry=0xffff880077a80c70 "/dev/loop4", data=data@entry=0x0 <irq_stack_union>) at namespace.c:813
  34  #11 0xffffffff811d55de in do_new_mount (data=0x0 <irq_stack_union>, name=0xffff880077a80c70 "/dev/loop4", mnt_flags=32,
  35      flags=<optimized out>, fstype=0xffff880077a80ca0 "ext4-insane", path=0xffff88007a5b1ed0) at namespace.c:2068
  36  #12 do_mount (dev_name=0xffff880077a80c70 "/dev/loop4", dir_name=<optimized out>, type_page=0xffff880077a80ca0 "ext4-insane",
  37      flags=<optimized out>, flags@entry=3236757504, data_page=0x0 <irq_stack_union>) at namespace.c:2392
  38  #13 0xffffffff811d6183 in SYSC_mount (data=0x0 <irq_stack_union>, flags=3236757504, type=<optimized out>, dir_name=<optimized out>,
  39      dev_name=0x7ffad9649c20 "/dev/loop4") at namespace.c:2586
  40  #14 SyS_mount (dev_name=140715365800992, dir_name=<optimized out>, type=<optimized out>, flags=3236757504, data=0) at namespace.c:2559
  41
  42 Signed-off-by: Azat Khuzhin <a3at.mail@gmail.com>
  43 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
  44 diff --git a/fs/ext4/super.c b/fs/ext4/super.c
  45 index 9a387b8..0491c81 100644
  46 --- a/fs/ext4/super.c
  47 +++ b/fs/ext4/super.c
  48 @@ -3848,16 +3848,34 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
  49                         goto failed_mount2;
  50                 }
  51         }
  52 +
  53 +       /*
  54 +        * set up enough so that it can read an inode
  55 +        */
  56 +       if (!test_opt(sb, NOLOAD) &&
  57 +           EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_HAS_JOURNAL))
  58 +               sb->s_op = &ext4_sops;
  59 +       else
  60 +               sb->s_op = &ext4_nojournal_sops;
  61 +
  62 +       ext4_ext_init(sb);
  63 +       err = ext4_mb_init(sb);
  64 +       if (err) {
  65 +               ext4_msg(sb, KERN_ERR, "failed to initialize mballoc (%d)",
  66 +                        err);
  67 +               goto failed_mount2;
  68 +       }
  69 +
  70         if (!ext4_check_descriptors(sb, &first_not_zeroed)) {
  71                 ext4_msg(sb, KERN_ERR, "group descriptors corrupted!");
  72 -               goto failed_mount2;
  73 +               goto failed_mount2a;
  74         }
  75         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG))
  76                 if (!ext4_fill_flex_info(sb)) {
  77                         ext4_msg(sb, KERN_ERR,
  78                                "unable to initialize "
  79                                "flex_bg meta info!");
  80 -                       goto failed_mount2;
  81 +                       goto failed_mount2a;
  82                 }
  83
  84         sbi->s_gdb_count = db_count;
  85 @@ -3895,14 +3913,6 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
  86         sbi->s_stripe = ext4_get_stripe_size(sbi);
  87         sbi->s_extent_max_zeroout_kb = 32;
  88
  89 -       /*
  90 -        * set up enough so that it can read an inode
  91 -        */
  92 -       if (!test_opt(sb, NOLOAD) &&
  93 -           EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_HAS_JOURNAL))
  94 -               sb->s_op = &ext4_sops;
  95 -       else
  96 -               sb->s_op = &ext4_nojournal_sops;
  97         sb->s_export_op = &ext4_export_ops;
  98         sb->s_xattr = ext4_xattr_handlers;
  99  #ifdef CONFIG_QUOTA
 100 @@ -4084,21 +4094,13 @@ no_journal:
 101         if (err) {
 102                 ext4_msg(sb, KERN_ERR, "failed to reserve %llu clusters for "
 103                          "reserved pool", ext4_calculate_resv_clusters(sb));
 104 -               goto failed_mount4a;
 105 +               goto failed_mount5;
 106         }
 107
 108         err = ext4_setup_system_zone(sb);
 109         if (err) {
 110                 ext4_msg(sb, KERN_ERR, "failed to initialize system "
 111                          "zone (%d)", err);
 112 -               goto failed_mount4a;
 113 -       }
 114 -
 115 -       ext4_ext_init(sb);
 116 -       err = ext4_mb_init(sb);
 117 -       if (err) {
 118 -               ext4_msg(sb, KERN_ERR, "failed to initialize mballoc (%d)",
 119 -                        err);
 120                 goto failed_mount5;
 121         }
 122
 123 @@ -4175,11 +4177,8 @@ failed_mount8:
 124  failed_mount7:
 125         ext4_unregister_li_request(sb);
 126  failed_mount6:
 127 -       ext4_mb_release(sb);
 128 -failed_mount5:
 129 -       ext4_ext_release(sb);
 130         ext4_release_system_zone(sb);
 131 -failed_mount4a:
 132 +failed_mount5:
 133         dput(sb->s_root);
 134         sb->s_root = NULL;
 135  failed_mount4:
 136 @@ -4203,11 +4202,14 @@ failed_mount3:
 137         percpu_counter_destroy(&sbi->s_extent_cache_cnt);
 138         if (sbi->s_mmp_tsk)
 139                 kthread_stop(sbi->s_mmp_tsk);
 140 +failed_mount2a:
 141 +       ext4_mb_release(sb);
 142  failed_mount2:
 143         for (i = 0; i < db_count; i++)
 144                 brelse(sbi->s_group_desc[i]);
 145         ext4_kvfree(sbi->s_group_desc);
 146  failed_mount:
 147 +       ext4_ext_release(sb);
 148         if (sbi->s_chksum_driver)
 149                 crypto_free_shash(sbi->s_chksum_driver);
 150         if (sbi->s_proc) {