Btrfs: avoid starting a transaction in the write path
I noticed while looking at a deadlock that we are always starting a transaction
in cow_file_range(). This isn't really needed since we only need a transaction
if we are doing an inline extent, or if the allocator needs to allocate a chunk.
So push down all the transaction start stuff to be closer to where we actually
need a transaction in all of these cases. This will hopefully reduce our write
latency when we are committing often. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index de7085b..264feef 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -230,12 +230,13 @@
* does the checks required to make sure the data is small enough
* to fit as an inline extent.
*/
-static noinline int cow_file_range_inline(struct btrfs_trans_handle *trans,
- struct btrfs_root *root,
- struct inode *inode, u64 start, u64 end,
- size_t compressed_size, int compress_type,
- struct page **compressed_pages)
+static noinline int cow_file_range_inline(struct btrfs_root *root,
+ struct inode *inode, u64 start,
+ u64 end, size_t compressed_size,
+ int compress_type,
+ struct page **compressed_pages)
{
+ struct btrfs_trans_handle *trans;
u64 isize = i_size_read(inode);
u64 actual_end = min(end + 1, isize);
u64 inline_len = actual_end - start;
@@ -256,9 +257,16 @@
return 1;
}
+ trans = btrfs_join_transaction(root);
+ if (IS_ERR(trans))
+ return PTR_ERR(trans);
+ trans->block_rsv = &root->fs_info->delalloc_block_rsv;
+
ret = btrfs_drop_extents(trans, root, inode, start, aligned_end, 1);
- if (ret)
- return ret;
+ if (ret) {
+ btrfs_abort_transaction(trans, root, ret);
+ goto out;
+ }
if (isize > actual_end)
inline_len = min_t(u64, isize, actual_end);
@@ -267,15 +275,18 @@
compress_type, compressed_pages);
if (ret && ret != -ENOSPC) {
btrfs_abort_transaction(trans, root, ret);
- return ret;
+ goto out;
} else if (ret == -ENOSPC) {
- return 1;
+ ret = 1;
+ goto out;
}
set_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &BTRFS_I(inode)->runtime_flags);
btrfs_delalloc_release_metadata(inode, end + 1 - start);
btrfs_drop_extent_cache(inode, start, aligned_end - 1, 0);
- return 0;
+out:
+ btrfs_end_transaction(trans, root);
+ return ret;
}
struct async_extent {
@@ -343,7 +354,6 @@
int *num_added)
{
struct btrfs_root *root = BTRFS_I(inode)->root;
- struct btrfs_trans_handle *trans;
u64 num_bytes;
u64 blocksize = root->sectorsize;
u64 actual_end;
@@ -461,25 +471,16 @@
}
cont:
if (start == 0) {
- trans = btrfs_join_transaction(root);
- if (IS_ERR(trans)) {
- ret = PTR_ERR(trans);
- trans = NULL;
- goto cleanup_and_out;
- }
- trans->block_rsv = &root->fs_info->delalloc_block_rsv;
-
/* lets try to make an inline extent */
if (ret || total_in < (actual_end - start)) {
/* we didn't compress the entire range, try
* to make an uncompressed inline extent.
*/
- ret = cow_file_range_inline(trans, root, inode,
- start, end, 0, 0, NULL);
+ ret = cow_file_range_inline(root, inode, start, end,
+ 0, 0, NULL);
} else {
/* try making a compressed inline extent */
- ret = cow_file_range_inline(trans, root, inode,
- start, end,
+ ret = cow_file_range_inline(root, inode, start, end,
total_compressed,
compress_type, pages);
}
@@ -498,10 +499,8 @@
PAGE_CLEAR_DIRTY |
PAGE_SET_WRITEBACK |
PAGE_END_WRITEBACK);
- btrfs_end_transaction(trans, root);
goto free_pages_out;
}
- btrfs_end_transaction(trans, root);
}
if (will_compress) {
@@ -592,18 +591,6 @@
kfree(pages);
goto out;
-
-cleanup_and_out:
- extent_clear_unlock_delalloc(inode, start, end, NULL,
- EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING |
- EXTENT_DEFRAG, PAGE_UNLOCK |
- PAGE_CLEAR_DIRTY | PAGE_SET_WRITEBACK |
- PAGE_END_WRITEBACK);
- if (!trans || IS_ERR(trans))
- btrfs_error(root->fs_info, ret, "Failed to join transaction");
- else
- btrfs_abort_transaction(trans, root, ret);
- goto free_pages_out;
}
/*
@@ -617,7 +604,6 @@
{
struct async_extent *async_extent;
u64 alloc_hint = 0;
- struct btrfs_trans_handle *trans;
struct btrfs_key ins;
struct extent_map *em;
struct btrfs_root *root = BTRFS_I(inode)->root;
@@ -678,20 +664,10 @@
lock_extent(io_tree, async_extent->start,
async_extent->start + async_extent->ram_size - 1);
- trans = btrfs_join_transaction(root);
- if (IS_ERR(trans)) {
- ret = PTR_ERR(trans);
- } else {
- trans->block_rsv = &root->fs_info->delalloc_block_rsv;
- ret = btrfs_reserve_extent(trans, root,
+ ret = btrfs_reserve_extent(root,
async_extent->compressed_size,
async_extent->compressed_size,
0, alloc_hint, &ins, 1);
- if (ret && ret != -ENOSPC)
- btrfs_abort_transaction(trans, root, ret);
- btrfs_end_transaction(trans, root);
- }
-
if (ret) {
int i;
@@ -850,14 +826,13 @@
* required to start IO on it. It may be clean and already done with
* IO when we return.
*/
-static noinline int __cow_file_range(struct btrfs_trans_handle *trans,
- struct inode *inode,
- struct btrfs_root *root,
- struct page *locked_page,
- u64 start, u64 end, int *page_started,
- unsigned long *nr_written,
- int unlock)
+static noinline int cow_file_range(struct inode *inode,
+ struct page *locked_page,
+ u64 start, u64 end, int *page_started,
+ unsigned long *nr_written,
+ int unlock)
{
+ struct btrfs_root *root = BTRFS_I(inode)->root;
u64 alloc_hint = 0;
u64 num_bytes;
unsigned long ram_size;
@@ -878,12 +853,12 @@
/* if this is a small write inside eof, kick off defrag */
if (num_bytes < 64 * 1024 &&
(start > 0 || end + 1 < BTRFS_I(inode)->disk_i_size))
- btrfs_add_inode_defrag(trans, inode);
+ btrfs_add_inode_defrag(NULL, inode);
if (start == 0) {
/* lets try to make an inline extent */
- ret = cow_file_range_inline(trans, root, inode,
- start, end, 0, 0, NULL);
+ ret = cow_file_range_inline(root, inode, start, end, 0, 0,
+ NULL);
if (ret == 0) {
extent_clear_unlock_delalloc(inode, start, end, NULL,
EXTENT_LOCKED | EXTENT_DELALLOC |
@@ -896,7 +871,6 @@
*page_started = 1;
goto out;
} else if (ret < 0) {
- btrfs_abort_transaction(trans, root, ret);
goto out_unlock;
}
}
@@ -911,13 +885,11 @@
unsigned long op;
cur_alloc_size = disk_num_bytes;
- ret = btrfs_reserve_extent(trans, root, cur_alloc_size,
+ ret = btrfs_reserve_extent(root, cur_alloc_size,
root->sectorsize, 0, alloc_hint,
&ins, 1);
- if (ret < 0) {
- btrfs_abort_transaction(trans, root, ret);
+ if (ret < 0)
goto out_unlock;
- }
em = alloc_extent_map();
if (!em) {
@@ -963,10 +935,8 @@
BTRFS_DATA_RELOC_TREE_OBJECTID) {
ret = btrfs_reloc_clone_csums(inode, start,
cur_alloc_size);
- if (ret) {
- btrfs_abort_transaction(trans, root, ret);
+ if (ret)
goto out_reserve;
- }
}
if (disk_num_bytes < cur_alloc_size)
@@ -1005,37 +975,6 @@
goto out;
}
-static noinline int cow_file_range(struct inode *inode,
- struct page *locked_page,
- u64 start, u64 end, int *page_started,
- unsigned long *nr_written,
- int unlock)
-{
- struct btrfs_trans_handle *trans;
- struct btrfs_root *root = BTRFS_I(inode)->root;
- int ret;
-
- trans = btrfs_join_transaction(root);
- if (IS_ERR(trans)) {
- extent_clear_unlock_delalloc(inode, start, end, locked_page,
- EXTENT_LOCKED | EXTENT_DELALLOC |
- EXTENT_DO_ACCOUNTING |
- EXTENT_DEFRAG, PAGE_UNLOCK |
- PAGE_CLEAR_DIRTY |
- PAGE_SET_WRITEBACK |
- PAGE_END_WRITEBACK);
- return PTR_ERR(trans);
- }
- trans->block_rsv = &root->fs_info->delalloc_block_rsv;
-
- ret = __cow_file_range(trans, inode, root, locked_page, start, end,
- page_started, nr_written, unlock);
-
- btrfs_end_transaction(trans, root);
-
- return ret;
-}
-
/*
* work queue call back to started compression on a file and pages
*/
@@ -1347,9 +1286,9 @@
btrfs_release_path(path);
if (cow_start != (u64)-1) {
- ret = __cow_file_range(trans, inode, root, locked_page,
- cow_start, found_key.offset - 1,
- page_started, nr_written, 1);
+ ret = cow_file_range(inode, locked_page,
+ cow_start, found_key.offset - 1,
+ page_started, nr_written, 1);
if (ret) {
btrfs_abort_transaction(trans, root, ret);
goto error;
@@ -1423,9 +1362,8 @@
}
if (cow_start != (u64)-1) {
- ret = __cow_file_range(trans, inode, root, locked_page,
- cow_start, end,
- page_started, nr_written, 1);
+ ret = cow_file_range(inode, locked_page, cow_start, end,
+ page_started, nr_written, 1);
if (ret) {
btrfs_abort_transaction(trans, root, ret);
goto error;
@@ -6344,39 +6282,32 @@
u64 start, u64 len)
{
struct btrfs_root *root = BTRFS_I(inode)->root;
- struct btrfs_trans_handle *trans;
struct extent_map *em;
struct btrfs_key ins;
u64 alloc_hint;
int ret;
- trans = btrfs_join_transaction(root);
- if (IS_ERR(trans))
- return ERR_CAST(trans);
-
- trans->block_rsv = &root->fs_info->delalloc_block_rsv;
-
alloc_hint = get_extent_allocation_hint(inode, start, len);
- ret = btrfs_reserve_extent(trans, root, len, root->sectorsize, 0,
+ ret = btrfs_reserve_extent(root, len, root->sectorsize, 0,
alloc_hint, &ins, 1);
- if (ret) {
- em = ERR_PTR(ret);
- goto out;
- }
+ if (ret)
+ return ERR_PTR(ret);
em = create_pinned_em(inode, start, ins.offset, start, ins.objectid,
ins.offset, ins.offset, ins.offset, 0);
- if (IS_ERR(em))
- goto out;
+ if (IS_ERR(em)) {
+ btrfs_free_reserved_extent(root, ins.objectid, ins.offset);
+ return em;
+ }
ret = btrfs_add_ordered_extent_dio(inode, start, ins.objectid,
ins.offset, ins.offset, 0);
if (ret) {
btrfs_free_reserved_extent(root, ins.objectid, ins.offset);
- em = ERR_PTR(ret);
+ free_extent_map(em);
+ return ERR_PTR(ret);
}
-out:
- btrfs_end_transaction(trans, root);
+
return em;
}
@@ -6384,11 +6315,11 @@
* returns 1 when the nocow is safe, < 1 on error, 0 if the
* block must be cow'd
*/
-noinline int can_nocow_extent(struct btrfs_trans_handle *trans,
- struct inode *inode, u64 offset, u64 *len,
+noinline int can_nocow_extent(struct inode *inode, u64 offset, u64 *len,
u64 *orig_start, u64 *orig_block_len,
u64 *ram_bytes)
{
+ struct btrfs_trans_handle *trans;
struct btrfs_path *path;
int ret;
struct extent_buffer *leaf;
@@ -6406,7 +6337,7 @@
if (!path)
return -ENOMEM;
- ret = btrfs_lookup_file_extent(trans, root, path, btrfs_ino(inode),
+ ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(inode),
offset, 0);
if (ret < 0)
goto out;
@@ -6471,9 +6402,19 @@
* look for other files referencing this extent, if we
* find any we must cow
*/
- if (btrfs_cross_ref_exist(trans, root, btrfs_ino(inode),
- key.offset - backref_offset, disk_bytenr))
+ trans = btrfs_join_transaction(root);
+ if (IS_ERR(trans)) {
+ ret = 0;
goto out;
+ }
+
+ ret = btrfs_cross_ref_exist(trans, root, btrfs_ino(inode),
+ key.offset - backref_offset, disk_bytenr);
+ btrfs_end_transaction(trans, root);
+ if (ret) {
+ ret = 0;
+ goto out;
+ }
/*
* adjust disk_bytenr and num_bytes to cover just the bytes
@@ -6615,7 +6556,6 @@
u64 start = iblock << inode->i_blkbits;
u64 lockstart, lockend;
u64 len = bh_result->b_size;
- struct btrfs_trans_handle *trans;
int unlock_bits = EXTENT_LOCKED;
int ret = 0;
@@ -6697,16 +6637,7 @@
len = min(len, em->len - (start - em->start));
block_start = em->block_start + (start - em->start);
- /*
- * we're not going to log anything, but we do need
- * to make sure the current transaction stays open
- * while we look for nocow cross refs
- */
- trans = btrfs_join_transaction(root);
- if (IS_ERR(trans))
- goto must_cow;
-
- if (can_nocow_extent(trans, inode, start, &len, &orig_start,
+ if (can_nocow_extent(inode, start, &len, &orig_start,
&orig_block_len, &ram_bytes) == 1) {
if (type == BTRFS_ORDERED_PREALLOC) {
free_extent_map(em);
@@ -6715,24 +6646,20 @@
block_start, len,
orig_block_len,
ram_bytes, type);
- if (IS_ERR(em)) {
- btrfs_end_transaction(trans, root);
+ if (IS_ERR(em))
goto unlock_err;
- }
}
ret = btrfs_add_ordered_extent_dio(inode, start,
block_start, len, len, type);
- btrfs_end_transaction(trans, root);
if (ret) {
free_extent_map(em);
goto unlock_err;
}
goto unlock;
}
- btrfs_end_transaction(trans, root);
}
-must_cow:
+
/*
* this will cow the extent, reset the len in case we changed
* it above
@@ -8495,8 +8422,8 @@
cur_bytes = min(num_bytes, 256ULL * 1024 * 1024);
cur_bytes = max(cur_bytes, min_size);
- ret = btrfs_reserve_extent(trans, root, cur_bytes,
- min_size, 0, *alloc_hint, &ins, 1);
+ ret = btrfs_reserve_extent(root, cur_bytes, min_size, 0,
+ *alloc_hint, &ins, 1);
if (ret) {
if (own_trans)
btrfs_end_transaction(trans, root);