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Message-ID: <4DA409E6.7020406@cn.fujitsu.com>
Date: Tue, 12 Apr 2011 16:14:30 +0800
From: Xiao Guangrong <xiaoguangrong@...fujitsu.com>
To: Chris Mason <chris.mason@...cle.com>
CC: LKML <linux-kernel@...r.kernel.org>,
BTRFS <linux-btrfs@...r.kernel.org>
Subject: [PATCH 1/2] Btrfs: allocate extent state and check the result properly
It doesn't allocate extent_state and check the result properly:
- in set_extent_bit, it doesn't allocate extent_state if the path is not
allowed wait
- in clear_extent_bit, it doesn't check the result after atomic-ly allocate,
we trigger BUG_ON() if it's fail
- if allocate fail, we trigger BUG_ON instead of returning -ENOMEM since
the return value of clear_extent_bit() is ignored by many callers
Signed-off-by: Xiao Guangrong <xiaoguangrong@...fujitsu.com>
---
fs/btrfs/extent_io.c | 29 +++++++++++++++++++++--------
1 files changed, 21 insertions(+), 8 deletions(-)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 77c65a0..62d5bca 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -439,6 +439,16 @@ static int clear_state_bit(struct extent_io_tree *tree,
return ret;
}
+static struct extent_state *
+alloc_extent_state_atomic(struct extent_state *prealloc)
+{
+ if (!prealloc)
+ prealloc = alloc_extent_state(GFP_ATOMIC);
+
+ BUG_ON(!prealloc);
+ return prealloc;
+}
+
/*
* clear some bits on a range in the tree. This may require splitting
* or inserting elements in the tree, so the gfp mask is used to
@@ -476,8 +486,7 @@ int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
again:
if (!prealloc && (mask & __GFP_WAIT)) {
prealloc = alloc_extent_state(mask);
- if (!prealloc)
- return -ENOMEM;
+ BUG_ON(!prealloc);
}
spin_lock(&tree->lock);
@@ -529,8 +538,7 @@ hit_next:
*/
if (state->start < start) {
- if (!prealloc)
- prealloc = alloc_extent_state(GFP_ATOMIC);
+ prealloc = alloc_extent_state_atomic(prealloc);
err = split_state(tree, state, prealloc, start);
BUG_ON(err == -EEXIST);
prealloc = NULL;
@@ -551,8 +559,7 @@ hit_next:
* on the first half
*/
if (state->start <= end && state->end > end) {
- if (!prealloc)
- prealloc = alloc_extent_state(GFP_ATOMIC);
+ prealloc = alloc_extent_state_atomic(prealloc);
err = split_state(tree, state, prealloc, end + 1);
BUG_ON(err == -EEXIST);
if (wake)
@@ -716,8 +723,7 @@ int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
again:
if (!prealloc && (mask & __GFP_WAIT)) {
prealloc = alloc_extent_state(mask);
- if (!prealloc)
- return -ENOMEM;
+ BUG_ON(!prealloc);
}
spin_lock(&tree->lock);
@@ -734,6 +740,7 @@ again:
*/
node = tree_search(tree, start);
if (!node) {
+ prealloc = alloc_extent_state_atomic(prealloc);
err = insert_state(tree, prealloc, start, end, &bits);
prealloc = NULL;
BUG_ON(err == -EEXIST);
@@ -802,6 +809,8 @@ hit_next:
err = -EEXIST;
goto out;
}
+
+ prealloc = alloc_extent_state_atomic(prealloc);
err = split_state(tree, state, prealloc, start);
BUG_ON(err == -EEXIST);
prealloc = NULL;
@@ -832,6 +841,8 @@ hit_next:
this_end = end;
else
this_end = last_start - 1;
+
+ prealloc = alloc_extent_state_atomic(prealloc);
err = insert_state(tree, prealloc, start, this_end,
&bits);
BUG_ON(err == -EEXIST);
@@ -856,6 +867,8 @@ hit_next:
err = -EEXIST;
goto out;
}
+
+ prealloc = alloc_extent_state_atomic(prealloc);
err = split_state(tree, state, prealloc, end + 1);
BUG_ON(err == -EEXIST);
--
1.7.4
--
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