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Btrfs: check if we can nocow if we don't have data space

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We always just try and reserve data space when we write, but if we are out of
space but have prealloc'ed extents we should still successfully write.  This
patch will try and see if we can write to prealloc'ed space and if we can go
ahead and allow the write to continue.  With this patch we now pass xfstests
generic/274.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
This commit is contained in:
Josef Bacik
2013-06-21 16:37:03 -04:00
parent 925a6efb8f
commit 7ee9e4405f
6 changed files with 148 additions and 26 deletions
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40
fs/btrfs/inode.c
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@@ -1641,7 +1641,7 @@ static void btrfs_clear_bit_hook(struct inode *inode,
btrfs_delalloc_release_metadata(inode, len);
if (root->root_key.objectid != BTRFS_DATA_RELOC_TREE_OBJECTID
&& do_list)
&& do_list && !(state->state & EXTENT_NORESERVE))
btrfs_free_reserved_data_space(inode, len);
__percpu_counter_add(&root->fs_info->delalloc_bytes, -len,
@@ -6396,10 +6396,10 @@ out:
* returns 1 when the nocow is safe, < 1 on error, 0 if the
* block must be cow'd
*/
static noinline int can_nocow_odirect(struct btrfs_trans_handle *trans,
struct inode *inode, u64 offset, u64 *len,
u64 *orig_start, u64 *orig_block_len,
u64 *ram_bytes)
noinline int can_nocow_extent(struct btrfs_trans_handle *trans,
struct inode *inode, u64 offset, u64 *len,
u64 *orig_start, u64 *orig_block_len,
u64 *ram_bytes)
{
struct btrfs_path *path;
int ret;
@@ -6413,7 +6413,7 @@ static noinline int can_nocow_odirect(struct btrfs_trans_handle *trans,
u64 num_bytes;
int slot;
int found_type;
bool nocow = (BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW);
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
@@ -6453,18 +6453,28 @@ static noinline int can_nocow_odirect(struct btrfs_trans_handle *trans,
/* not a regular extent, must cow */
goto out;
}
if (!nocow && found_type == BTRFS_FILE_EXTENT_REG)
goto out;
disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
if (disk_bytenr == 0)
goto out;
if (btrfs_file_extent_compression(leaf, fi) ||
btrfs_file_extent_encryption(leaf, fi) ||
btrfs_file_extent_other_encoding(leaf, fi))
goto out;
backref_offset = btrfs_file_extent_offset(leaf, fi);
*orig_start = key.offset - backref_offset;
*orig_block_len = btrfs_file_extent_disk_num_bytes(leaf, fi);
*ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);
if (orig_start) {
*orig_start = key.offset - backref_offset;
*orig_block_len = btrfs_file_extent_disk_num_bytes(leaf, fi);
*ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);
}
extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
if (extent_end < offset + *len) {
/* extent doesn't include our full range, must cow */
goto out;
}
if (btrfs_extent_readonly(root, disk_bytenr))
goto out;
@@ -6708,8 +6718,8 @@ static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock,
if (IS_ERR(trans))
goto must_cow;
if (can_nocow_odirect(trans, inode, start, &len, &orig_start,
&orig_block_len, &ram_bytes) == 1) {
if (can_nocow_extent(trans, inode, start, &len, &orig_start,
&orig_block_len, &ram_bytes) == 1) {
if (type == BTRFS_ORDERED_PREALLOC) {
free_extent_map(em);
em = create_pinned_em(inode, start, len,