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.
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
13 unsigned long s_ext_extents;
16 + /* maximum possible extents tree depth, to be computed at mount time */
17 + unsigned int s_max_ext_tree_depth;
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
27 if (ext4_multi_mount_protect(sb, le64_to_cpu(es->s_mmp_block)))
30 + ext4_ext_init(sb); /* needed before using extent-mapped journal */
33 * The first inode we look at is the journal inode. Don't try
34 * root first: it may be modified in the journal!
40 err = ext4_mb_init(sb, needs_recovery);
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
49 /* account possible depth increase */
51 - path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 2),
53 + path = kzalloc(sizeof(struct ext4_ext_path) *
54 + (EXT4_SB(inode->i_sb)->s_max_ext_tree_depth + 1),
57 return ERR_PTR(-ENOMEM);
59 @@ -1985,12 +1986,6 @@
63 - if (ext_depth(inode) != depth) {
64 - /* depth was changed. we have to realloc path */
69 block = cbex.ec_block + cbex.ec_len;
73 * after i_size and walking into the tree depth-wise.
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 + 1),
81 ext4_journal_stop(handle);
83 @@ -2755,13 +2751,15 @@
85 void ext4_ext_init(struct super_block *sb)
87 + ext4_fsblk_t maxblocks;
90 * possible initialization would be here
93 if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS)) {
94 -#if defined(AGGRESSIVE_TEST) || defined(CHECK_BINSEARCH) || defined(EXTENTS_STATS)
95 - printk(KERN_INFO "EXT4-fs: file extents enabled");
96 + printk(KERN_INFO "EXT4-fs (%s): file extents enabled",
98 #ifdef AGGRESSIVE_TEST
99 printk(", aggressive tests");
101 @@ -2770,14 +2768,35 @@
108 -#ifdef EXTENTS_STATS
109 spin_lock_init(&EXT4_SB(sb)->s_ext_stats_lock);
110 EXT4_SB(sb)->s_ext_min = 1 << 30;
111 EXT4_SB(sb)->s_ext_max = 0;
113 + EXT4_SB(sb)->s_max_ext_tree_depth = 1;
115 + maxblocks = sb->s_maxbytes / sb->s_blocksize;
117 + /* 1st/root level/node of extents tree stands in i_data and
118 + * entries stored in tree nodes can be of type ext4_extent
119 + * (leaf node) or ext4_extent_idx (internal node) */
120 + maxblocks /= (sizeof(((struct ext4_inode_info *)0x0)->i_data) -
121 + sizeof(struct ext4_extent_header)) /
122 + max(sizeof(struct ext4_extent),
123 + sizeof(struct ext4_extent_idx));
125 + /* compute maximum extents tree depth for a fully populated
126 + * file of max size made of only minimal/1-block extents */
127 + while (maxblocks > 0) {
128 + maxblocks /= (sb->s_blocksize -
129 + sizeof(struct ext4_extent_header)) /
130 + max(sizeof(struct ext4_extent),
131 + sizeof(struct ext4_extent_idx));
132 + EXT4_SB(sb)->s_max_ext_tree_depth++;
135 + printk(", maximum tree depth=%u",
136 + EXT4_SB(sb)->s_max_ext_tree_depth);
141 @@ -3592,15 +3611,10 @@
142 * the start of the hole
144 ext4_ext_drop_refs(path);
147 + /* keep/reuse path */
148 path = ext4_ext_find_extent(inode,
149 - map->m_lblk, NULL);
150 - if (IS_ERR(path)) {
151 - err = PTR_ERR(path);
155 + map->m_lblk, path);
157 depth = ext_depth(inode);
158 ex = path[depth].p_ext;