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Btrfs: avoid starting a transaction in the write path

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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>
This commit is contained in:
Josef Bacik 2013-08-14 14:02:47 -04:00 committed by Chris Mason
parent 9ffba8cda9
commit 00361589d2
6 changed files with 101 additions and 179 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
fs/btrfs/ctree.h
View File

@ -3165,11 +3165,9 @@ int btrfs_alloc_logged_file_extent(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
u64 root_objectid, u64 owner, u64 offset,
struct btrfs_key *ins);
int btrfs_reserve_extent(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
u64 num_bytes, u64 min_alloc_size,
u64 empty_size, u64 hint_byte,
struct btrfs_key *ins, int is_data);
int btrfs_reserve_extent(struct btrfs_root *root, u64 num_bytes,
u64 min_alloc_size, u64 empty_size, u64 hint_byte,
struct btrfs_key *ins, int is_data);
int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
struct extent_buffer *buf, int full_backref, int for_cow);
int btrfs_dec_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
@ -3612,8 +3610,7 @@ void btrfs_wait_and_free_delalloc_work(struct btrfs_delalloc_work *work);
struct extent_map *btrfs_get_extent_fiemap(struct inode *inode, struct page *page,
size_t pg_offset, u64 start, u64 len,
int create);
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);

35
fs/btrfs/extent-tree.c
View File

@ -6121,8 +6121,7 @@ enum btrfs_loop_type {
* ins->offset == number of blocks
* Any available blocks before search_start are skipped.
*/
static noinline int find_free_extent(struct btrfs_trans_handle *trans,
struct btrfs_root *orig_root,
static noinline int find_free_extent(struct btrfs_root *orig_root,
u64 num_bytes, u64 empty_size,
u64 hint_byte, struct btrfs_key *ins,
u64 flags)
@ -6345,10 +6344,10 @@ refill_cluster:
block_group->full_stripe_len);
/* allocate a cluster in this block group */
ret = btrfs_find_space_cluster(trans, root,
block_group, last_ptr,
search_start, num_bytes,
aligned_cluster);
ret = btrfs_find_space_cluster(root, block_group,
last_ptr, search_start,
num_bytes,
aligned_cluster);
if (ret == 0) {
/*
* now pull our allocation out of this
@ -6479,17 +6478,28 @@ loop:
index = 0;
loop++;
if (loop == LOOP_ALLOC_CHUNK) {
struct btrfs_trans_handle *trans;
trans = btrfs_join_transaction(root);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
goto out;
}
ret = do_chunk_alloc(trans, root, flags,
CHUNK_ALLOC_FORCE);
/*
* Do not bail out on ENOSPC since we
* can do more things.
*/
if (ret < 0 && ret != -ENOSPC) {
if (ret < 0 && ret != -ENOSPC)
btrfs_abort_transaction(trans,
root, ret);
else
ret = 0;
btrfs_end_transaction(trans, root);
if (ret)
goto out;
}
}
if (loop == LOOP_NO_EMPTY_SIZE) {
@ -6553,8 +6563,7 @@ again:
up_read(&info->groups_sem);
}
int btrfs_reserve_extent(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
int btrfs_reserve_extent(struct btrfs_root *root,
u64 num_bytes, u64 min_alloc_size,
u64 empty_size, u64 hint_byte,
struct btrfs_key *ins, int is_data)
@ -6566,8 +6575,8 @@ int btrfs_reserve_extent(struct btrfs_trans_handle *trans,
flags = btrfs_get_alloc_profile(root, is_data);
again:
WARN_ON(num_bytes < root->sectorsize);
ret = find_free_extent(trans, root, num_bytes, empty_size,
hint_byte, ins, flags);
ret = find_free_extent(root, num_bytes, empty_size, hint_byte, ins,
flags);
if (ret == -ENOSPC) {
if (!final_tried) {
@ -6955,7 +6964,7 @@ struct extent_buffer *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
if (IS_ERR(block_rsv))
return ERR_CAST(block_rsv);
ret = btrfs_reserve_extent(trans, root, blocksize, blocksize,
ret = btrfs_reserve_extent(root, blocksize, blocksize,
empty_size, hint, &ins, 0);
if (ret) {
unuse_block_rsv(root->fs_info, block_rsv, blocksize);

11
fs/btrfs/file.c
View File

@ -1339,7 +1339,6 @@ fail:
static noinline int check_can_nocow(struct inode *inode, loff_t pos,
size_t *write_bytes)
{
struct btrfs_trans_handle *trans;
struct btrfs_root *root = BTRFS_I(inode)->root;
struct btrfs_ordered_extent *ordered;
u64 lockstart, lockend;
@ -1361,16 +1360,8 @@ static noinline int check_can_nocow(struct inode *inode, loff_t pos,
btrfs_put_ordered_extent(ordered);
}
trans = btrfs_join_transaction(root);
if (IS_ERR(trans)) {
unlock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend);
return PTR_ERR(trans);
}
num_bytes = lockend - lockstart + 1;
ret = can_nocow_extent(trans, inode, lockstart, &num_bytes, NULL, NULL,
NULL);
btrfs_end_transaction(trans, root);
ret = can_nocow_extent(inode, lockstart, &num_bytes, NULL, NULL, NULL);
if (ret <= 0) {
ret = 0;
} else {

3
fs/btrfs/free-space-cache.c
View File

@ -2525,8 +2525,7 @@ setup_cluster_bitmap(struct btrfs_block_group_cache *block_group,
* returns zero and sets up cluster if things worked out, otherwise
* it returns -enospc
*/
int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
int btrfs_find_space_cluster(struct btrfs_root *root,
struct btrfs_block_group_cache *block_group,
struct btrfs_free_cluster *cluster,
u64 offset, u64 bytes, u64 empty_size)

3
fs/btrfs/free-space-cache.h
View File

@ -98,8 +98,7 @@ u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
u64 btrfs_find_ino_for_alloc(struct btrfs_root *fs_root);
void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
u64 bytes);
int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
int btrfs_find_space_cluster(struct btrfs_root *root,
struct btrfs_block_group_cache *block_group,
struct btrfs_free_cluster *cluster,
u64 offset, u64 bytes, u64 empty_size);

217
fs/btrfs/inode.c
View File

@ -230,12 +230,13 @@ fail:
* 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 @@ static noinline int cow_file_range_inline(struct btrfs_trans_handle *trans,
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 @@ static noinline int cow_file_range_inline(struct btrfs_trans_handle *trans,
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 @@ static noinline int compress_file_range(struct inode *inode,
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 @@ again:
}
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 @@ cont:
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 @@ free_pages_out:
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 @@ static noinline int submit_compressed_extents(struct inode *inode,
{
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 @@ retry:
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 @@ static u64 get_extent_allocation_hint(struct inode *inode, u64 start,
* 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 @@ static noinline int __cow_file_range(struct btrfs_trans_handle *trans,
/* 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 @@ static noinline int __cow_file_range(struct btrfs_trans_handle *trans,
*page_started = 1;
goto out;
} else if (ret < 0) {
btrfs_abort_transaction(trans, root, ret);
goto out_unlock;
}
}
@ -911,13 +885,11 @@ static noinline int __cow_file_range(struct btrfs_trans_handle *trans,
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 @@ static noinline int __cow_file_range(struct btrfs_trans_handle *trans,
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 @@ out_unlock:
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 @@ out_check:
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 @@ out_check:
}
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 @@ static struct extent_map *btrfs_new_extent_direct(struct inode *inode,
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 @@ out:
* 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 @@ noinline int can_nocow_extent(struct btrfs_trans_handle *trans,
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 @@ noinline int can_nocow_extent(struct btrfs_trans_handle *trans,
* 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 @@ static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock,
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 @@ static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock,
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 @@ static int btrfs_get_blocks_direct(struct inode *inode, sector_t iblock,
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 @@ static int __btrfs_prealloc_file_range(struct inode *inode, int mode,
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);