* [PATCH 1/3] btrfs: remove unnecessary -ENOMEM BUG_ON check in extent-tree.c/exclude_super_stripes
@ 2012-09-06 6:40 Wang Sheng-Hui
2012-09-06 10:09 ` David Sterba
0 siblings, 1 reply; 3+ messages in thread
From: Wang Sheng-Hui @ 2012-09-06 6:40 UTC (permalink / raw)
To: chris.mason, linux-btrfs, linux-kernel
The memory allocation failure is BUG_ON in add_excluded_extent (following
the code path) and btrfs_rmap_block. No need to BUG_ON -ENOMEM inside
exclude_super_stripes itself.
Its return value is always 0, and useless for its callers. Set it as void
instead 0-returned.
Signed-off-by: Wang Sheng-Hui <shhuiw@gmail.com>
---
fs/btrfs/extent-tree.c | 20 +++++++-------------
1 files changed, 7 insertions(+), 13 deletions(-)
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index ba58024..95492cc 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -234,39 +234,33 @@ static void free_excluded_extents(struct btrfs_root *root,
start, end, EXTENT_UPTODATE, GFP_NOFS);
}
-static int exclude_super_stripes(struct btrfs_root *root,
+static void exclude_super_stripes(struct btrfs_root *root,
struct btrfs_block_group_cache *cache)
{
u64 bytenr;
u64 *logical;
int stripe_len;
- int i, nr, ret;
+ int i, nr;
if (cache->key.objectid < BTRFS_SUPER_INFO_OFFSET) {
stripe_len = BTRFS_SUPER_INFO_OFFSET - cache->key.objectid;
cache->bytes_super += stripe_len;
- ret = add_excluded_extent(root, cache->key.objectid,
- stripe_len);
- BUG_ON(ret); /* -ENOMEM */
+ add_excluded_extent(root, cache->key.objectid, stripe_len);
}
for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
bytenr = btrfs_sb_offset(i);
- ret = btrfs_rmap_block(&root->fs_info->mapping_tree,
- cache->key.objectid, bytenr,
- 0, &logical, &nr, &stripe_len);
- BUG_ON(ret); /* -ENOMEM */
+ btrfs_rmap_block(&root->fs_info->mapping_tree,
+ cache->key.objectid, bytenr,
+ 0, &logical, &nr, &stripe_len);
while (nr--) {
cache->bytes_super += stripe_len;
- ret = add_excluded_extent(root, logical[nr],
- stripe_len);
- BUG_ON(ret); /* -ENOMEM */
+ add_excluded_extent(root, logical[nr], stripe_len);
}
kfree(logical);
}
- return 0;
}
static struct btrfs_caching_control *
--
1.7.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH 1/3] btrfs: remove unnecessary -ENOMEM BUG_ON check in extent-tree.c/exclude_super_stripes
2012-09-06 6:40 [PATCH 1/3] btrfs: remove unnecessary -ENOMEM BUG_ON check in extent-tree.c/exclude_super_stripes Wang Sheng-Hui
@ 2012-09-06 10:09 ` David Sterba
2012-09-06 14:12 ` Wang Sheng-Hui
0 siblings, 1 reply; 3+ messages in thread
From: David Sterba @ 2012-09-06 10:09 UTC (permalink / raw)
To: Wang Sheng-Hui; +Cc: chris.mason, linux-btrfs, linux-kernel
On Thu, Sep 06, 2012 at 02:40:41PM +0800, Wang Sheng-Hui wrote:
> The memory allocation failure is BUG_ON in add_excluded_extent (following
> the code path) and btrfs_rmap_block. No need to BUG_ON -ENOMEM inside
> exclude_super_stripes itself.
No please.
> Its return value is always 0, and useless for its callers. Set it as void
> instead 0-returned.
btrfs_rmap_block itself contains a BUG_ON:
3980 int btrfs_rmap_block(struct btrfs_mapping_tree *map_tree,
3981 u64 chunk_start, u64 physical, u64 devid,
3982 u64 **logical, int *naddrs, int *stripe_len)
3983 {
3984 struct extent_map_tree *em_tree = &map_tree->map_tree;
3985 struct extent_map *em;
3986 struct map_lookup *map;
3987 u64 *buf;
3988 u64 bytenr;
3989 u64 length;
3990 u64 stripe_nr;
3991 int i, j, nr = 0;
3992
3993 read_lock(&em_tree->lock);
3994 em = lookup_extent_mapping(em_tree, chunk_start, 1);
3995 read_unlock(&em_tree->lock);
3996
3997 BUG_ON(!em || em->start != chunk_start);
And this should be turned into an 'return error', thus giving a non-zero return
code that should be handled in the callers.
Eg. this patch attempts to do that
http://www.mail-archive.com/linux-btrfs@vger.kernel.org/msg15470.html
but has not been merged due to incorrect fix inside exclude_super_stripes
(introduced in the patch).
The same objection for return code cleanups will hold for any function that
returns 0 but is full of BUG_ONs.
david
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH 1/3] btrfs: remove unnecessary -ENOMEM BUG_ON check in extent-tree.c/exclude_super_stripes
2012-09-06 10:09 ` David Sterba
@ 2012-09-06 14:12 ` Wang Sheng-Hui
0 siblings, 0 replies; 3+ messages in thread
From: Wang Sheng-Hui @ 2012-09-06 14:12 UTC (permalink / raw)
To: chris.mason, linux-btrfs, linux-kernel
On 2012年09月06日 18:09, David Sterba wrote:
> On Thu, Sep 06, 2012 at 02:40:41PM +0800, Wang Sheng-Hui wrote:
>> The memory allocation failure is BUG_ON in add_excluded_extent (following
>> the code path) and btrfs_rmap_block. No need to BUG_ON -ENOMEM inside
>> exclude_super_stripes itself.
>
> No please.
>
>> Its return value is always 0, and useless for its callers. Set it as void
>> instead 0-returned.
>
> btrfs_rmap_block itself contains a BUG_ON:
>
> 3980 int btrfs_rmap_block(struct btrfs_mapping_tree *map_tree,
> 3981 u64 chunk_start, u64 physical, u64 devid,
> 3982 u64 **logical, int *naddrs, int *stripe_len)
> 3983 {
> 3984 struct extent_map_tree *em_tree = &map_tree->map_tree;
> 3985 struct extent_map *em;
> 3986 struct map_lookup *map;
> 3987 u64 *buf;
> 3988 u64 bytenr;
> 3989 u64 length;
> 3990 u64 stripe_nr;
> 3991 int i, j, nr = 0;
> 3992
> 3993 read_lock(&em_tree->lock);
> 3994 em = lookup_extent_mapping(em_tree, chunk_start, 1);
> 3995 read_unlock(&em_tree->lock);
> 3996
> 3997 BUG_ON(!em || em->start != chunk_start);
>
> And this should be turned into an 'return error', thus giving a non-zero return
> code that should be handled in the callers.
>
> Eg. this patch attempts to do that
> http://www.mail-archive.com/linux-btrfs@vger.kernel.org/msg15470.html
>
> but has not been merged due to incorrect fix inside exclude_super_stripes
> (introduced in the patch).
>
> The same objection for return code cleanups will hold for any function that
> returns 0 but is full of BUG_ONs.
>
>
> david
Got it. Thanks, David!
Regards,
Sheng-Hui
^ permalink raw reply [flat|nested] 3+ messages in thread
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2012-09-06 6:40 [PATCH 1/3] btrfs: remove unnecessary -ENOMEM BUG_ON check in extent-tree.c/exclude_super_stripes Wang Sheng-Hui
2012-09-06 10:09 ` David Sterba
2012-09-06 14:12 ` Wang Sheng-Hui
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