Wang Shilong
2014-Jun-28 11:06 UTC
[PATCH RFC] Btrfs: make defragment work with nodatacow option
Btrfs defragment will utilize COW feature, which means this
did not work for nodatacow option, this problem was detected
by xfstests generic/018 with nodatacow mount option.
Fix this problem by forcing cow for a extent with state
@EXTETN_DEFRAG setting.
Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
---
fs/btrfs/btrfs_inode.h | 6 ++++++
fs/btrfs/inode.c | 39 ++++++++++++++++++++++++++++++++++++---
2 files changed, 42 insertions(+), 3 deletions(-)
diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 4794923..4e9265a 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -127,6 +127,12 @@ struct btrfs_inode {
u64 delalloc_bytes;
/*
+ * total number of bytes pending defrag, used by stat to check whether
+ * it needs COW.
+ */
+ u64 defrag_bytes;
+
+ /*
* the size of the file stored in the metadata on disk. data=ordered
* means the in-memory i_size might be larger than the size on disk
* because not all the blocks are written yet.
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 3668048..4a203fb 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1425,6 +1425,26 @@ error:
return ret;
}
+static inline int need_force_cow(struct inode *inode, u64 start, u64 end)
+{
+
+ if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW) &&
+ !(BTRFS_I(inode)->flags & BTRFS_INODE_PREALLOC))
+ return 0;
+
+ /*
+ * @defrag_bytes is a hint value, no spinlock held here,
+ * if is not zero, it means the file is defragging.
+ * Force cow if given extent needs to be defragged.
+ */
+ if (BTRFS_I(inode)->defrag_bytes &&
+ test_range_bit(&BTRFS_I(inode)->io_tree, start, end,
+ EXTENT_DEFRAG, 0, NULL))
+ return 1;
+
+ return 0;
+}
+
/*
* extent_io.c call back to do delayed allocation processing
*/
@@ -1434,11 +1454,12 @@ static int run_delalloc_range(struct inode *inode,
struct page *locked_page,
{
int ret;
struct btrfs_root *root = BTRFS_I(inode)->root;
+ int force_cow = need_force_cow(inode, start, end);
- if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW) {
+ if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW &&
!force_cow) {
ret = run_delalloc_nocow(inode, locked_page, start, end,
page_started, 1, nr_written);
- } else if (BTRFS_I(inode)->flags & BTRFS_INODE_PREALLOC) {
+ } else if (BTRFS_I(inode)->flags & BTRFS_INODE_PREALLOC &&
!force_cow) {
ret = run_delalloc_nocow(inode, locked_page, start, end,
page_started, 0, nr_written);
} else if (!btrfs_test_opt(root, COMPRESS) &&
@@ -1535,6 +1556,8 @@ static void btrfs_set_bit_hook(struct inode *inode,
struct extent_state *state, unsigned long *bits)
{
+ if ((*bits & EXTENT_DEFRAG) && !(*bits & EXTENT_DELALLOC))
+ WARN_ON(1);
/*
* set_bit and clear bit hooks normally require _irqsave/restore
* but in this case, we are only testing for the DELALLOC
@@ -1557,6 +1580,8 @@ static void btrfs_set_bit_hook(struct inode *inode,
root->fs_info->delalloc_batch);
spin_lock(&BTRFS_I(inode)->lock);
BTRFS_I(inode)->delalloc_bytes += len;
+ if (*bits & EXTENT_DEFRAG)
+ BTRFS_I(inode)->defrag_bytes += len;
if (do_list && !test_bit(BTRFS_INODE_IN_DELALLOC_LIST,
&BTRFS_I(inode)->runtime_flags))
btrfs_add_delalloc_inodes(root, inode);
@@ -1571,6 +1596,13 @@ static void btrfs_clear_bit_hook(struct inode *inode,
struct extent_state *state,
unsigned long *bits)
{
+ u64 len = state->end + 1 - state->start;
+
+ spin_lock(&BTRFS_I(inode)->lock);
+ if ((state->state & EXTENT_DEFRAG) && (*bits &
EXTENT_DEFRAG))
+ BTRFS_I(inode)->defrag_bytes -= len;
+ spin_unlock(&BTRFS_I(inode)->lock);
+
/*
* set_bit and clear bit hooks normally require _irqsave/restore
* but in this case, we are only testing for the DELALLOC
@@ -1578,7 +1610,6 @@ static void btrfs_clear_bit_hook(struct inode *inode,
*/
if ((state->state & EXTENT_DELALLOC) && (*bits &
EXTENT_DELALLOC)) {
struct btrfs_root *root = BTRFS_I(inode)->root;
- u64 len = state->end + 1 - state->start;
bool do_list = !btrfs_is_free_space_inode(inode);
if (*bits & EXTENT_FIRST_DELALLOC) {
@@ -8078,6 +8109,7 @@ struct inode *btrfs_alloc_inode(struct super_block *sb)
ei->last_sub_trans = 0;
ei->logged_trans = 0;
ei->delalloc_bytes = 0;
+ ei->defrag_bytes = 0;
ei->disk_i_size = 0;
ei->flags = 0;
ei->csum_bytes = 0;
@@ -8137,6 +8169,7 @@ void btrfs_destroy_inode(struct inode *inode)
WARN_ON(BTRFS_I(inode)->reserved_extents);
WARN_ON(BTRFS_I(inode)->delalloc_bytes);
WARN_ON(BTRFS_I(inode)->csum_bytes);
+ WARN_ON(BTRFS_I(inode)->defrag_bytes);
/*
* This can happen where we create an inode, but somebody else also
--
1.8.3.1
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