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Btrfs: fix bad extent logging 

A user sent me a btrfs-image of a file system that was panicing on mount during
the log recovery.  I had originally thought these problems were from a bug in
the free space cache code, but that was just a symptom of the problem.  The
problem is if your application does something like this

[prealloc][prealloc][prealloc]

the internal extent maps will merge those all together into one extent map, even
though on disk they are 3 separate extents.  So if you go to write into one of
these ranges the extent map will be right since we use the physical extent when
doing the write, but when we log the extents they will use the wrong sizes for
the remainder prealloc space.  If this doesn't happen to trip up the free space
cache (which it won't in a lot of cases) then you will get bogus entries in your
extent tree which will screw stuff up later.  The data and such will still work,
but everything else is broken.  This patch fixes this by not allowing extents
that are on the modified list to be merged.  This has the side effect that we
are no longer adding everything to the modified list all the time, which means
we now have to call btrfs_drop_extents every time we log an extent into the
tree.  So this allows me to drop all this speciality code I was using to get
around calling btrfs_drop_extents.  With this patch the testcase I've created no
longer creates a bogus file system after replaying the log.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
This commit is contained in:
Josef Bacik 2013-04-05 16:51:15 -04:00
parent cc95bef635
commit 09a2a8f96e
10 changed files with 40 additions and 324 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

140
fs/btrfs/ctree.c
View File

@ -2211,9 +2211,6 @@ static noinline void unlock_up(struct btrfs_path *path, int level,
int no_skips = 0;
struct extent_buffer *t;
if (path->really_keep_locks)
return;
for (i = level; i < BTRFS_MAX_LEVEL; i++) {
if (!path->nodes[i])
break;
@ -2261,7 +2258,7 @@ noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level)
{
int i;
if (path->keep_locks || path->really_keep_locks)
if (path->keep_locks)
return;
for (i = level; i < BTRFS_MAX_LEVEL; i++) {
@ -2494,7 +2491,7 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
if (!cow)
write_lock_level = -1;
if (cow && (p->really_keep_locks || p->keep_locks || p->lowest_level))
if (cow && (p->keep_locks || p->lowest_level))
write_lock_level = BTRFS_MAX_LEVEL;
min_write_lock_level = write_lock_level;
@ -5465,139 +5462,6 @@ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
return btrfs_next_old_leaf(root, path, 0);
}
/* Release the path up to but not including the given level */
static void btrfs_release_level(struct btrfs_path *path, int level)
{
int i;
for (i = 0; i < level; i++) {
path->slots[i] = 0;
if (!path->nodes[i])
continue;
if (path->locks[i]) {
btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]);
path->locks[i] = 0;
}
free_extent_buffer(path->nodes[i]);
path->nodes[i] = NULL;
}
}
/*
* This function assumes 2 things
*
* 1) You are using path->keep_locks
* 2) You are not inserting items.
*
* If either of these are not true do not use this function. If you need a next
* leaf with either of these not being true then this function can be easily
* adapted to do that, but at the moment these are the limitations.
*/
int btrfs_next_leaf_write(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct btrfs_path *path,
int del)
{
struct extent_buffer *b;
struct btrfs_key key;
u32 nritems;
int level = 1;
int slot;
int ret = 1;
int write_lock_level = BTRFS_MAX_LEVEL;
int ins_len = del ? -1 : 0;
WARN_ON(!(path->keep_locks || path->really_keep_locks));
nritems = btrfs_header_nritems(path->nodes[0]);
btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
while (path->nodes[level]) {
nritems = btrfs_header_nritems(path->nodes[level]);
if (!(path->locks[level] & BTRFS_WRITE_LOCK)) {
search:
btrfs_release_path(path);
ret = btrfs_search_slot(trans, root, &key, path,
ins_len, 1);
if (ret < 0)
goto out;
level = 1;
continue;
}
if (path->slots[level] >= nritems - 1) {
level++;
continue;
}
btrfs_release_level(path, level);
break;
}
if (!path->nodes[level]) {
ret = 1;
goto out;
}
path->slots[level]++;
b = path->nodes[level];
while (b) {
level = btrfs_header_level(b);
if (!should_cow_block(trans, root, b))
goto cow_done;
btrfs_set_path_blocking(path);
ret = btrfs_cow_block(trans, root, b,
path->nodes[level + 1],
path->slots[level + 1], &b);
if (ret)
goto out;
cow_done:
path->nodes[level] = b;
btrfs_clear_path_blocking(path, NULL, 0);
if (level != 0) {
ret = setup_nodes_for_search(trans, root, path, b,
level, ins_len,
&write_lock_level);
if (ret == -EAGAIN)
goto search;
if (ret)
goto out;
b = path->nodes[level];
slot = path->slots[level];
ret = read_block_for_search(trans, root, path,
&b, level, slot, &key, 0);
if (ret == -EAGAIN)
goto search;
if (ret)
goto out;
level = btrfs_header_level(b);
if (!btrfs_try_tree_write_lock(b)) {
btrfs_set_path_blocking(path);
btrfs_tree_lock(b);
btrfs_clear_path_blocking(path, b,
BTRFS_WRITE_LOCK);
}
path->locks[level] = BTRFS_WRITE_LOCK;
path->nodes[level] = b;
path->slots[level] = 0;
} else {
path->slots[level] = 0;
ret = 0;
break;
}
}
out:
if (ret)
btrfs_release_path(path);
return ret;
}
int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
u64 time_seq)
{

4
fs/btrfs/ctree.h
View File

@ -586,7 +586,6 @@ struct btrfs_path {
unsigned int skip_locking:1;
unsigned int leave_spinning:1;
unsigned int search_commit_root:1;
unsigned int really_keep_locks:1;
};
/*
@ -3273,9 +3272,6 @@ static inline int btrfs_insert_empty_item(struct btrfs_trans_handle *trans,
}
int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path);
int btrfs_next_leaf_write(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct btrfs_path *path,
int del);
int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
u64 time_seq);
static inline int btrfs_next_old_item(struct btrfs_root *root,

2
fs/btrfs/disk-io.c
View File

@ -222,7 +222,7 @@ static struct extent_map *btree_get_extent(struct inode *inode,
em->bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev;
write_lock(&em_tree->lock);
ret = add_extent_mapping(em_tree, em);
ret = add_extent_mapping(em_tree, em, 0);
if (ret == -EEXIST) {
free_extent_map(em);
em = lookup_extent_mapping(em_tree, start, len);

18
fs/btrfs/extent_map.c
View File

@ -174,6 +174,14 @@ static int mergable_maps(struct extent_map *prev, struct extent_map *next)
test_bit(EXTENT_FLAG_LOGGING, &next->flags))
return 0;
/*
* We don't want to merge stuff that hasn't been written to the log yet
* since it may not reflect exactly what is on disk, and that would be
* bad.
*/
if (!list_empty(&prev->list) || !list_empty(&next->list))
return 0;
if (extent_map_end(prev) == next->start &&
prev->flags == next->flags &&
prev->bdev == next->bdev &&
@ -209,9 +217,7 @@ static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em)
em->mod_len = (em->mod_len + em->mod_start) - merge->mod_start;
em->mod_start = merge->mod_start;
em->generation = max(em->generation, merge->generation);
list_move(&em->list, &tree->modified_extents);
list_del_init(&merge->list);
rb_erase(&merge->rb_node, &tree->map);
free_extent_map(merge);
}
@ -227,7 +233,6 @@ static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em)
merge->in_tree = 0;
em->mod_len = (merge->mod_start + merge->mod_len) - em->mod_start;
em->generation = max(em->generation, merge->generation);
list_del_init(&merge->list);
free_extent_map(merge);
}
}
@ -302,7 +307,7 @@ void clear_em_logging(struct extent_map_tree *tree, struct extent_map *em)
* reference dropped if the merge attempt was successful.
*/
int add_extent_mapping(struct extent_map_tree *tree,
struct extent_map *em)
struct extent_map *em, int modified)
{
int ret = 0;
struct rb_node *rb;
@ -324,7 +329,10 @@ int add_extent_mapping(struct extent_map_tree *tree,
em->mod_start = em->start;
em->mod_len = em->len;
try_merge_map(tree, em);
if (modified)
list_move(&em->list, &tree->modified_extents);
else
try_merge_map(tree, em);
out:
return ret;
}

2
fs/btrfs/extent_map.h
View File

@ -62,7 +62,7 @@ void extent_map_tree_init(struct extent_map_tree *tree);
struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
u64 start, u64 len);
int add_extent_mapping(struct extent_map_tree *tree,
struct extent_map *em);
struct extent_map *em, int modified);
int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em);
struct extent_map *alloc_extent_map(void);

14
fs/btrfs/file.c
View File

@ -552,6 +552,7 @@ void btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
int testend = 1;
unsigned long flags;
int compressed = 0;
bool modified;
WARN_ON(end < start);
if (end == (u64)-1) {
@ -561,6 +562,7 @@ void btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
while (1) {
int no_splits = 0;
modified = false;
if (!split)
split = alloc_extent_map();
if (!split2)
@ -592,6 +594,7 @@ void btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
clear_bit(EXTENT_FLAG_PINNED, &em->flags);
clear_bit(EXTENT_FLAG_LOGGING, &flags);
modified = !list_empty(&em->list);
remove_extent_mapping(em_tree, em);
if (no_splits)
goto next;
@ -614,9 +617,8 @@ void btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
split->bdev = em->bdev;
split->flags = flags;
split->compress_type = em->compress_type;
ret = add_extent_mapping(em_tree, split);
ret = add_extent_mapping(em_tree, split, modified);
BUG_ON(ret); /* Logic error */
list_move(&split->list, &em_tree->modified_extents);
free_extent_map(split);
split = split2;
split2 = NULL;
@ -645,9 +647,8 @@ void btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
split->orig_start = em->orig_start;
}
ret = add_extent_mapping(em_tree, split);
ret = add_extent_mapping(em_tree, split, modified);
BUG_ON(ret); /* Logic error */
list_move(&split->list, &em_tree->modified_extents);
free_extent_map(split);
split = NULL;
}
@ -1930,10 +1931,7 @@ out:
do {
btrfs_drop_extent_cache(inode, offset, end - 1, 0);
write_lock(&em_tree->lock);
ret = add_extent_mapping(em_tree, hole_em);
if (!ret)
list_move(&hole_em->list,
&em_tree->modified_extents);
ret = add_extent_mapping(em_tree, hole_em, 1);
write_unlock(&em_tree->lock);
} while (ret == -EEXIST);
free_extent_map(hole_em);

34
fs/btrfs/inode.c
View File

@ -732,10 +732,7 @@ retry:
while (1) {
write_lock(&em_tree->lock);
ret = add_extent_mapping(em_tree, em);
if (!ret)
list_move(&em->list,
&em_tree->modified_extents);
ret = add_extent_mapping(em_tree, em, 1);
write_unlock(&em_tree->lock);
if (ret != -EEXIST) {
free_extent_map(em);
@ -941,10 +938,7 @@ static noinline int __cow_file_range(struct btrfs_trans_handle *trans,
while (1) {
write_lock(&em_tree->lock);
ret = add_extent_mapping(em_tree, em);
if (!ret)
list_move(&em->list,
&em_tree->modified_extents);
ret = add_extent_mapping(em_tree, em, 1);
write_unlock(&em_tree->lock);
if (ret != -EEXIST) {
free_extent_map(em);
@ -1387,10 +1381,7 @@ out_check:
em->generation = -1;
while (1) {
write_lock(&em_tree->lock);
ret = add_extent_mapping(em_tree, em);
if (!ret)
list_move(&em->list,
&em_tree->modified_extents);
ret = add_extent_mapping(em_tree, em, 1);
write_unlock(&em_tree->lock);
if (ret != -EEXIST) {
free_extent_map(em);
@ -4467,10 +4458,7 @@ int btrfs_cont_expand(struct inode *inode, loff_t oldsize, loff_t size)
while (1) {
write_lock(&em_tree->lock);
err = add_extent_mapping(em_tree, hole_em);
if (!err)
list_move(&hole_em->list,
&em_tree->modified_extents);
err = add_extent_mapping(em_tree, hole_em, 1);
write_unlock(&em_tree->lock);
if (err != -EEXIST)
break;
@ -5989,7 +5977,7 @@ static int merge_extent_mapping(struct extent_map_tree *em_tree,
em->block_start += start_diff;
em->block_len -= start_diff;
}
return add_extent_mapping(em_tree, em);
return add_extent_mapping(em_tree, em, 0);
}
static noinline int uncompress_inline(struct btrfs_path *path,
@ -6283,7 +6271,7 @@ insert:
err = 0;
write_lock(&em_tree->lock);
ret = add_extent_mapping(em_tree, em);
ret = add_extent_mapping(em_tree, em, 0);
/* it is possible that someone inserted the extent into the tree
* while we had the lock dropped. It is also possible that
* an overlapping map exists in the tree
@ -6706,10 +6694,7 @@ static struct extent_map *create_pinned_em(struct inode *inode, u64 start,
btrfs_drop_extent_cache(inode, em->start,
em->start + em->len - 1, 0);
write_lock(&em_tree->lock);
ret = add_extent_mapping(em_tree, em);
if (!ret)
list_move(&em->list,
&em_tree->modified_extents);
ret = add_extent_mapping(em_tree, em, 1);
write_unlock(&em_tree->lock);
} while (ret == -EEXIST);
@ -8593,10 +8578,7 @@ static int __btrfs_prealloc_file_range(struct inode *inode, int mode,
while (1) {
write_lock(&em_tree->lock);
ret = add_extent_mapping(em_tree, em);
if (!ret)
list_move(&em->list,
&em_tree->modified_extents);
ret = add_extent_mapping(em_tree, em, 1);
write_unlock(&em_tree->lock);
if (ret != -EEXIST)
break;

2
fs/btrfs/relocation.c
View File

@ -2979,7 +2979,7 @@ int setup_extent_mapping(struct inode *inode, u64 start, u64 end,
lock_extent(&BTRFS_I(inode)->io_tree, start, end);
while (1) {
write_lock(&em_tree->lock);
ret = add_extent_mapping(em_tree, em);
ret = add_extent_mapping(em_tree, em, 0);
write_unlock(&em_tree->lock);
if (ret != -EEXIST) {
free_extent_map(em);

144
fs/btrfs/tree-log.c
View File

@ -3209,115 +3209,6 @@ static int extent_cmp(void *priv, struct list_head *a, struct list_head *b)
return 0;
}
static int drop_adjacent_extents(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct inode *inode,
struct extent_map *em,
struct btrfs_path *path)
{
struct btrfs_file_extent_item *fi;
struct extent_buffer *leaf;
struct btrfs_key key, new_key;
struct btrfs_map_token token;
u64 extent_end;
u64 extent_offset = 0;
int extent_type;
int del_slot = 0;
int del_nr = 0;
int ret = 0;
while (1) {
btrfs_init_map_token(&token);
leaf = path->nodes[0];
path->slots[0]++;
if (path->slots[0] >= btrfs_header_nritems(leaf)) {
if (del_nr) {
ret = btrfs_del_items(trans, root, path,
del_slot, del_nr);
if (ret)
return ret;
del_nr = 0;
}
ret = btrfs_next_leaf_write(trans, root, path, 1);
if (ret < 0)
return ret;
if (ret > 0)
return 0;
leaf = path->nodes[0];
}
btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
if (key.objectid != btrfs_ino(inode) ||
key.type != BTRFS_EXTENT_DATA_KEY ||
key.offset >= em->start + em->len)
break;
fi = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
extent_type = btrfs_token_file_extent_type(leaf, fi, &token);
if (extent_type == BTRFS_FILE_EXTENT_REG ||
extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
extent_offset = btrfs_token_file_extent_offset(leaf,
fi, &token);
extent_end = key.offset +
btrfs_token_file_extent_num_bytes(leaf, fi,
&token);
} else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
extent_end = key.offset +
btrfs_file_extent_inline_len(leaf, fi);
} else {
BUG();
}
if (extent_end <= em->len + em->start) {
if (!del_nr) {
del_slot = path->slots[0];
}
del_nr++;
continue;
}
/*
* Ok so we'll ignore previous items if we log a new extent,
* which can lead to overlapping extents, so if we have an
* existing extent we want to adjust we _have_ to check the next
* guy to make sure we even need this extent anymore, this keeps
* us from panicing in set_item_key_safe.
*/
if (path->slots[0] < btrfs_header_nritems(leaf) - 1) {
struct btrfs_key tmp_key;
btrfs_item_key_to_cpu(leaf, &tmp_key,
path->slots[0] + 1);
if (tmp_key.objectid == btrfs_ino(inode) &&
tmp_key.type == BTRFS_EXTENT_DATA_KEY &&
tmp_key.offset <= em->start + em->len) {
if (!del_nr)
del_slot = path->slots[0];
del_nr++;
continue;
}
}
BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
memcpy(&new_key, &key, sizeof(new_key));
new_key.offset = em->start + em->len;
btrfs_set_item_key_safe(trans, root, path, &new_key);
extent_offset += em->start + em->len - key.offset;
btrfs_set_token_file_extent_offset(leaf, fi, extent_offset,
&token);
btrfs_set_token_file_extent_num_bytes(leaf, fi, extent_end -
(em->start + em->len),
&token);
btrfs_mark_buffer_dirty(leaf);
}
if (del_nr)
ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
return ret;
}
static int log_one_extent(struct btrfs_trans_handle *trans,
struct inode *inode, struct btrfs_root *root,
struct extent_map *em, struct btrfs_path *path)
@ -3339,39 +3230,24 @@ static int log_one_extent(struct btrfs_trans_handle *trans,
int index = log->log_transid % 2;
bool skip_csum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM;
insert:
ret = __btrfs_drop_extents(trans, log, inode, path, em->start,
em->start + em->len, NULL, 0);
if (ret)
return ret;
INIT_LIST_HEAD(&ordered_sums);
btrfs_init_map_token(&token);
key.objectid = btrfs_ino(inode);
key.type = BTRFS_EXTENT_DATA_KEY;
key.offset = em->start;
path->really_keep_locks = 1;
ret = btrfs_insert_empty_item(trans, log, path, &key, sizeof(*fi));
if (ret && ret != -EEXIST) {
path->really_keep_locks = 0;
if (ret)
return ret;
}
leaf = path->nodes[0];
fi = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
/*
* If we are overwriting an inline extent with a real one then we need
* to just delete the inline extent as it may not be large enough to
* have the entire file_extent_item.
*/
if (ret && btrfs_token_file_extent_type(leaf, fi, &token) ==
BTRFS_FILE_EXTENT_INLINE) {
ret = btrfs_del_item(trans, log, path);
btrfs_release_path(path);
if (ret) {
path->really_keep_locks = 0;
return ret;
}
goto insert;
}
btrfs_set_token_file_extent_generation(leaf, fi, em->generation,
&token);
if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) {
@ -3417,15 +3293,7 @@ insert:
btrfs_set_token_file_extent_other_encoding(leaf, fi, 0, &token);
btrfs_mark_buffer_dirty(leaf);
/*
* Have to check the extent to the right of us to make sure it doesn't
* fall in our current range. We're ok if the previous extent is in our
* range since the recovery stuff will run us in key order and thus just
* drop the part we overwrote.
*/
ret = drop_adjacent_extents(trans, log, inode, em, path);
btrfs_release_path(path);
path->really_keep_locks = 0;
if (ret) {
return ret;
}

4
fs/btrfs/volumes.c
View File

@ -3932,7 +3932,7 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
em_tree = &extent_root->fs_info->mapping_tree.map_tree;
write_lock(&em_tree->lock);
ret = add_extent_mapping(em_tree, em);
ret = add_extent_mapping(em_tree, em, 0);
write_unlock(&em_tree->lock);
if (ret) {
free_extent_map(em);
@ -5476,7 +5476,7 @@ static int read_one_chunk(struct btrfs_root *root, struct btrfs_key *key,
}
write_lock(&map_tree->map_tree.lock);
ret = add_extent_mapping(&map_tree->map_tree, em);
ret = add_extent_mapping(&map_tree->map_tree, em, 0);
write_unlock(&map_tree->map_tree.lock);
BUG_ON(ret); /* Tree corruption */
free_extent_map(em);