ldiskfs/kernel_patches/patches/sles11sp3/ext4_s_max_ext_tree_depth.patch

   1 Fix ext4_ext_find_extent() to already pre-allocate ext4_ext_path[]
   2 array of the max depth instead of current depth.
   3 This will avoid racy cases of concurrent ext_depth() growth in
   4 current and unsafe implementation with ext4_ext_path[] array
   5 re-[sizing,allocation], even with more recent and related patches
   6 that will be integrated in more recent Kernels.
   7
   8 Index: linux-2.6.32-504.el6.x86_64/fs/ext4/ext4.h
   9 ===================================================================
  10 --- linux-2.6.32-504.el6.x86_64.orig/fs/ext4/ext4.h
  11 +++ linux-2.6.32-504.el6.x86_64/fs/ext4/ext4.h
  12 @@ -1147,6 +1147,9 @@
  13         unsigned long s_ext_extents;
  14  #endif
  15
  16 +       /* maximum possible extents tree depth, to be computed at mount time */
  17 +       unsigned int s_max_ext_tree_depth;
  18 +
  19         /* for buddy allocator */
  20         struct ext4_group_info ***s_group_info;
  21         struct inode *s_buddy_cache;
  22 Index: linux-2.6.32-504.el6.x86_64/fs/ext4/super.c
  23 ===================================================================
  24 --- linux-2.6.32-504.el6.x86_64.orig/fs/ext4/super.c
  25 +++ linux-2.6.32-504.el6.x86_64/fs/ext4/super.c
  26 @@ -3529,6 +3529,8 @@
  27                 if (ext4_multi_mount_protect(sb, le64_to_cpu(es->s_mmp_block)))
  28                         goto failed_mount3;
  29
  30 +       ext4_ext_init(sb); /* needed before using extent-mapped journal */
  31 +
  32         /*
  33          * The first inode we look at is the journal inode.  Don't try
  34          * root first: it may be modified in the journal!
  35 @@ -3722,7 +3724,6 @@
  36                 goto failed_mount4a;
  37         }
  38
  39 -       ext4_ext_init(sb);
  40         err = ext4_mb_init(sb, needs_recovery);
  41         if (err) {
  42                 ext4_msg(sb, KERN_ERR, "failed to initalize mballoc (%d)",
  43 Index: linux-2.6.32-504.el6.x86_64/fs/ext4/extents.c
  44 ===================================================================
  45 --- linux-2.6.32-504.el6.x86_64.orig/fs/ext4/extents.c
  46 +++ linux-2.6.32-504.el6.x86_64/fs/ext4/extents.c
  47 @@ -687,8 +687,9 @@
  48
  49         /* account possible depth increase */
  50         if (!path) {
  51 -               path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 2),
  52 -                               GFP_NOFS);
  53 +               path = kzalloc(sizeof(struct ext4_ext_path) *
  54 +                              EXT4_SB(inode->i_sb)->s_max_ext_tree_depth,
  55 +                              GFP_NOFS);
  56                 if (!path)
  57                         return ERR_PTR(-ENOMEM);
  58                 alloc = 1;
  59 @@ -1985,12 +1986,6 @@
  60                         break;
  61                 }
  62
  63 -               if (ext_depth(inode) != depth) {
  64 -                       /* depth was changed. we have to realloc path */
  65 -                       kfree(path);
  66 -                       path = NULL;
  67 -               }
  68 -
  69                 block = cbex.ec_block + cbex.ec_len;
  70         }
  71
  72 @@ -2636,7 +2631,8 @@
  73          * after i_size and walking into the tree depth-wise.
  74          */
  75         depth = ext_depth(inode);
  76 -       path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 1), GFP_NOFS);
  77 +       path = kzalloc(sizeof(struct ext4_ext_path) *
  78 +                      EXT4_SB(inode->i_sb)->s_max_ext_tree_depth, GFP_NOFS);
  79         if (path == NULL) {
  80                 ext4_journal_stop(handle);
  81                 return -ENOMEM;
  82 @@ -2755,13 +2751,15 @@
  83   */
  84  void ext4_ext_init(struct super_block *sb)
  85  {
  86 +       ext4_fsblk_t maxblocks;
  87 +
  88         /*
  89          * possible initialization would be here
  90          */
  91
  92         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS)) {
  93 -#if defined(AGGRESSIVE_TEST) || defined(CHECK_BINSEARCH) || defined(EXTENTS_STATS)
  94 -               printk(KERN_INFO "EXT4-fs: file extents enabled");
  95 +               printk(KERN_INFO "EXT4-fs (%s): file extents enabled",
  96 +                      sb->s_id);
  97  #ifdef AGGRESSIVE_TEST
  98                 printk(", aggressive tests");
  99  #endif
 100 @@ -2770,14 +2768,35 @@
 101  #endif
 102  #ifdef EXTENTS_STATS
 103                 printk(", stats");
 104 -#endif
 105 -               printk("\n");
 106 -#endif
 107 -#ifdef EXTENTS_STATS
 108                 spin_lock_init(&EXT4_SB(sb)->s_ext_stats_lock);
 109                 EXT4_SB(sb)->s_ext_min = 1 << 30;
 110                 EXT4_SB(sb)->s_ext_max = 0;
 111  #endif
 112 +               EXT4_SB(sb)->s_max_ext_tree_depth = 1;
 113 +
 114 +               maxblocks = sb->s_maxbytes / sb->s_blocksize;
 115 +
 116 +               /* 1st/root level/node of extents tree stands in i_data and
 117 +                * entries stored in tree nodes can be of type ext4_extent
 118 +                * (leaf node) or ext4_extent_idx (internal node) */
 119 +               maxblocks /= (sizeof(((struct ext4_inode_info *)0x0)->i_data) -
 120 +                             sizeof(struct ext4_extent_header)) /
 121 +                            max(sizeof(struct ext4_extent),
 122 +                                sizeof(struct ext4_extent_idx));
 123 +
 124 +               /* compute maximum extents tree depth for a fully populated
 125 +                * file of max size made of only minimal/1-block extents */
 126 +               while (maxblocks > 0) {
 127 +                       maxblocks /= (sb->s_blocksize -
 128 +                                     sizeof(struct ext4_extent_header)) /
 129 +                                    max(sizeof(struct ext4_extent),
 130 +                                        sizeof(struct ext4_extent_idx));
 131 +                       EXT4_SB(sb)->s_max_ext_tree_depth++;
 132 +               }
 133 +
 134 +               printk(", maximum tree depth=%u",
 135 +                      EXT4_SB(sb)->s_max_ext_tree_depth);
 136 +               printk("\n");
 137         }
 138  }
 139
 140 @@ -3592,15 +3611,10 @@
 141                                  * the start of the hole
 142                                  */
 143                                 ext4_ext_drop_refs(path);
 144 -                               kfree(path);
 145
 146 +                               /* keep/reuse path */
 147                                 path = ext4_ext_find_extent(inode,
 148 -                               map->m_lblk, NULL);
 149 -                               if (IS_ERR(path)) {
 150 -                                       err = PTR_ERR(path);
 151 -                                       path = NULL;
 152 -                                       goto out2;
 153 -                               }
 154 +                                                           map->m_lblk, path);
 155
 156                                 depth = ext_depth(inode);
 157                                 ex = path[depth].p_ext;