Viewing: ext4-mballoc-extra-checks.patch
commit f2f28f1d09c0a00b3fc569422f881931d857fac9
Author: Alex Zhuravlev <alex.zhuravlev@sun.com>
AuthorDate: Tue Oct 28 17:59:09 2008 +0000
Subject: ext4: detect on-disk corruption of block bitmap
Detect on-disk corruption of block bitmap and better checking of
preallocated blocks.
Bugzilla-ID: b=16680
Signed-off-by: Alex Zhuravlev <alex.zhuravlev@sun.com>
Reviewed-by: Kalpak Shah <kalpak.shah@sun.com>
Signed-off-by: Andreas Dilger <andreas.dilger@sun.com>
Index: linux-4.18.0-80.1.2.el8_0/fs/ext4/ext4.h
===================================================================
--- linux-4.18.0-80.1.2.el8_0.orig/fs/ext4/ext4.h
+++ linux-4.18.0-80.1.2.el8_0/fs/ext4/ext4.h
@@ -2881,6 +2881,7 @@ struct ext4_group_info {
ext4_grpblk_t bb_fragments; /* nr of freespace fragments */
ext4_grpblk_t bb_largest_free_order;/* order of largest frag in BG */
struct list_head bb_prealloc_list;
+ unsigned long bb_prealloc_nr;
#ifdef DOUBLE_CHECK
void *bb_bitmap;
#endif
Index: linux-4.18.0-80.1.2.el8_0/fs/ext4/mballoc.c
===================================================================
--- linux-4.18.0-80.1.2.el8_0.orig/fs/ext4/mballoc.c
+++ linux-4.18.0-80.1.2.el8_0/fs/ext4/mballoc.c
@@ -352,7 +352,7 @@ static const char * const ext4_groupinfo
"ext4_groupinfo_64k", "ext4_groupinfo_128k"
};
-static void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
+static int ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
ext4_group_t group);
static void ext4_mb_generate_from_freelist(struct super_block *sb, void *bitmap,
ext4_group_t group);
@@ -708,7 +708,7 @@ mb_set_largest_free_order(struct super_b
}
static noinline_for_stack
-void ext4_mb_generate_buddy(struct super_block *sb,
+int ext4_mb_generate_buddy(struct super_block *sb,
void *buddy, void *bitmap, ext4_group_t group)
{
struct ext4_group_info *grp = ext4_get_group_info(sb, group);
@@ -752,6 +752,7 @@ void ext4_mb_generate_buddy(struct super
grp->bb_free = free;
ext4_mark_group_bitmap_corrupted(sb, group,
EXT4_GROUP_INFO_BBITMAP_CORRUPT);
+ return -EIO;
}
mb_set_largest_free_order(sb, grp);
@@ -762,6 +763,8 @@ void ext4_mb_generate_buddy(struct super
sbi->s_mb_buddies_generated++;
sbi->s_mb_generation_time += period;
spin_unlock(&sbi->s_bal_lock);
+
+ return 0;
}
static void mb_regenerate_buddy(struct ext4_buddy *e4b)
@@ -882,7 +885,7 @@ static int ext4_mb_init_cache(struct pag
}
first_block = page->index * blocks_per_page;
- for (i = 0; i < blocks_per_page; i++) {
+ for (i = 0; i < blocks_per_page && err == 0; i++) {
group = (first_block + i) >> 1;
if (group >= ngroups)
break;
@@ -926,7 +929,7 @@ static int ext4_mb_init_cache(struct pag
ext4_lock_group(sb, group);
/* init the buddy */
memset(data, 0xff, blocksize);
- ext4_mb_generate_buddy(sb, data, incore, group);
+ err = ext4_mb_generate_buddy(sb, data, incore, group);
ext4_unlock_group(sb, group);
incore = NULL;
} else {
@@ -941,7 +944,7 @@ static int ext4_mb_init_cache(struct pag
memcpy(data, bitmap, blocksize);
/* mark all preallocated blks used in in-core bitmap */
- ext4_mb_generate_from_pa(sb, data, group);
+ err = ext4_mb_generate_from_pa(sb, data, group);
ext4_mb_generate_from_freelist(sb, data, group);
ext4_unlock_group(sb, group);
@@ -951,7 +954,8 @@ static int ext4_mb_init_cache(struct pag
incore = data;
}
}
- SetPageUptodate(page);
+ if (likely(err == 0))
+ SetPageUptodate(page);
out:
if (bh) {
@@ -2280,9 +2284,11 @@ static void *ext4_mb_seq_groups_next(str
static int ext4_mb_seq_groups_show(struct seq_file *seq, void *v)
{
struct super_block *sb = PDE_DATA(file_inode(seq->file));
+ struct ext4_group_desc *gdp;
ext4_group_t group = (ext4_group_t) ((unsigned long) v);
int i;
int err, buddy_loaded = 0;
+ int free = 0;
struct ext4_buddy e4b;
struct ext4_group_info *grinfo;
unsigned char blocksize_bits = min_t(unsigned char,
@@ -2295,7 +2301,7 @@ static int ext4_mb_seq_groups_show(struc
group--;
if (group == 0)
- seq_puts(seq, "#group: free frags first ["
+ seq_puts(seq, "#group: bfree gfree frags first pa ["
" 2^0 2^1 2^2 2^3 2^4 2^5 2^6 "
" 2^7 2^8 2^9 2^10 2^11 2^12 2^13 ]\n");
@@ -2313,13 +2319,19 @@ static int ext4_mb_seq_groups_show(struc
buddy_loaded = 1;
}
+ gdp = ext4_get_group_desc(sb, group, NULL);
+ if (gdp != NULL)
+ free = ext4_free_group_clusters(sb, gdp);
+
memcpy(&sg, ext4_get_group_info(sb, group), i);
if (buddy_loaded)
ext4_mb_unload_buddy(&e4b);
- seq_printf(seq, "#%-5u: %-5u %-5u %-5u [", group, sg.info.bb_free,
- sg.info.bb_fragments, sg.info.bb_first_free);
+ seq_printf(seq, "#%-5lu: %-5u %-5u %-5u %-5u %-5lu [",
+ (long unsigned int)group, sg.info.bb_free, free,
+ sg.info.bb_fragments, sg.info.bb_first_free,
+ sg.info.bb_prealloc_nr);
for (i = 0; i <= 13; i++)
seq_printf(seq, " %-5u", i <= blocksize_bits + 1 ?
sg.info.bb_counters[i] : 0);
@@ -3614,22 +3626,71 @@ static void ext4_mb_generate_from_freeli
}
/*
+ * check free blocks in bitmap match free block in group descriptor
+ * do this before taking preallocated blocks into account to be able
+ * to detect on-disk corruptions. The group lock should be hold by the
+ * caller.
+ */
+int ext4_mb_check_ondisk_bitmap(struct super_block *sb, void *bitmap,
+ struct ext4_group_desc *gdp, int group)
+{
+ unsigned short max = EXT4_CLUSTERS_PER_GROUP(sb);
+ unsigned short i, first, free = 0;
+ unsigned short free_in_gdp = ext4_free_group_clusters(sb, gdp);
+
+ if (free_in_gdp == 0 && gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))
+ return 0;
+
+ i = mb_find_next_zero_bit(bitmap, max, 0);
+
+ while (i < max) {
+ first = i;
+ i = mb_find_next_bit(bitmap, max, i);
+ if (i > max)
+ i = max;
+ free += i - first;
+ if (i < max)
+ i = mb_find_next_zero_bit(bitmap, max, i);
+ }
+
+ if (free != free_in_gdp) {
+ ext4_error(sb, "on-disk bitmap for group %d"
+ "corrupted: %u blocks free in bitmap, %u - in gd\n",
+ group, free, free_in_gdp);
+ return -EIO;
+ }
+ return 0;
+}
+
+/*
* the function goes through all preallocation in this group and marks them
* used in in-core bitmap. buddy must be generated from this bitmap
* Need to be called with ext4 group lock held
*/
static noinline_for_stack
-void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
+int ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
ext4_group_t group)
{
struct ext4_group_info *grp = ext4_get_group_info(sb, group);
struct ext4_prealloc_space *pa;
+ struct ext4_group_desc *gdp;
struct list_head *cur;
ext4_group_t groupnr;
ext4_grpblk_t start;
int preallocated = 0;
+ int skip = 0, count = 0;
+ int err;
int len;
+ gdp = ext4_get_group_desc(sb, group, NULL);
+ if (gdp == NULL)
+ return -EIO;
+
+ /* before applying preallocations, check bitmap consistency */
+ err = ext4_mb_check_ondisk_bitmap(sb, bitmap, gdp, group);
+ if (err)
+ return err;
+
/* all form of preallocation discards first load group,
* so the only competing code is preallocation use.
* we don't need any locking here
@@ -3645,13 +3706,23 @@ void ext4_mb_generate_from_pa(struct sup
&groupnr, &start);
len = pa->pa_len;
spin_unlock(&pa->pa_lock);
- if (unlikely(len == 0))
+ if (unlikely(len == 0)) {
+ skip++;
continue;
+ }
BUG_ON(groupnr != group);
ext4_set_bits(bitmap, start, len);
preallocated += len;
+ count++;
+ }
+ if (count + skip != grp->bb_prealloc_nr) {
+ ext4_error(sb, "lost preallocations: "
+ "count %d, bb_prealloc_nr %lu, skip %d\n",
+ count, grp->bb_prealloc_nr, skip);
+ return -EIO;
}
mb_debug(1, "preallocated %u for group %u\n", preallocated, group);
+ return 0;
}
static void ext4_mb_pa_callback(struct rcu_head *head)
@@ -3715,6 +3786,7 @@ static void ext4_mb_put_pa(struct ext4_a
*/
ext4_lock_group(sb, grp);
list_del(&pa->pa_group_list);
+ ext4_get_group_info(sb, grp)->bb_prealloc_nr--;
ext4_unlock_group(sb, grp);
spin_lock(pa->pa_obj_lock);
@@ -3809,6 +3881,7 @@ ext4_mb_new_inode_pa(struct ext4_allocat
ext4_lock_group(sb, ac->ac_b_ex.fe_group);
list_add(&pa->pa_group_list, &grp->bb_prealloc_list);
+ grp->bb_prealloc_nr++;
ext4_unlock_group(sb, ac->ac_b_ex.fe_group);
spin_lock(pa->pa_obj_lock);
@@ -3870,6 +3943,7 @@ ext4_mb_new_group_pa(struct ext4_allocat
ext4_lock_group(sb, ac->ac_b_ex.fe_group);
list_add(&pa->pa_group_list, &grp->bb_prealloc_list);
+ grp->bb_prealloc_nr++;
ext4_unlock_group(sb, ac->ac_b_ex.fe_group);
/*
@@ -4041,6 +4115,8 @@ repeat:
spin_unlock(&pa->pa_lock);
+ BUG_ON(grp->bb_prealloc_nr == 0);
+ grp->bb_prealloc_nr--;
list_del(&pa->pa_group_list);
list_add(&pa->u.pa_tmp_list, &list);
}
@@ -4171,7 +4247,7 @@ repeat:
if (err) {
ext4_error(sb, "Error %d loading buddy information for %u",
err, group);
- continue;
+ return;
}
bitmap_bh = ext4_read_block_bitmap(sb, group);
@@ -4184,6 +4260,8 @@ repeat:
}
ext4_lock_group(sb, group);
+ BUG_ON(e4b.bd_info->bb_prealloc_nr == 0);
+ e4b.bd_info->bb_prealloc_nr--;
list_del(&pa->pa_group_list);
ext4_mb_release_inode_pa(&e4b, bitmap_bh, pa);
ext4_unlock_group(sb, group);
@@ -4446,6 +4524,7 @@ ext4_mb_discard_lg_preallocations(struct
}
ext4_lock_group(sb, group);
list_del(&pa->pa_group_list);
+ ext4_get_group_info(sb, group)->bb_prealloc_nr--;
ext4_mb_release_group_pa(&e4b, pa);
ext4_unlock_group(sb, group);
Index: linux-4.18.0-80.1.2.el8_0/fs/ext4/mballoc.h
===================================================================
--- linux-4.18.0-80.1.2.el8_0.orig/fs/ext4/mballoc.h
+++ linux-4.18.0-80.1.2.el8_0/fs/ext4/mballoc.h
@@ -70,7 +70,7 @@ do { \
/*
* for which requests use 2^N search using buddies
*/
-#define MB_DEFAULT_ORDER2_REQS 2
+#define MB_DEFAULT_ORDER2_REQS 8
/*
* default group prealloc size 512 blocks
