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btrfs: cleanup the COW fallback logic in run_delalloc_nocow 

Use the block group pointer used to track the outstanding NOCOW writes as
a boolean to remove the duplicate nocow variable, and keep it contained
in the main loop to simplify the logic.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Christoph Hellwig 2023-07-24 07:22:39 -07:00 committed by David Sterba
parent 953fa5ced5
commit 18f62b86c4
1 changed files with 22 additions and 25 deletions
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47
fs/btrfs/inode.c
View File

@ -1974,8 +1974,6 @@ static noinline int run_delalloc_nocow(struct btrfs_inode *inode,
int ret;
bool check_prev = true;
u64 ino = btrfs_ino(inode);
struct btrfs_block_group *bg;
bool nocow = false;
struct can_nocow_file_extent_args nocow_args = { 0 };
path = btrfs_alloc_path();
@ -1993,6 +1991,7 @@ static noinline int run_delalloc_nocow(struct btrfs_inode *inode,
nocow_args.writeback_path = true;
while (1) {
struct btrfs_block_group *nocow_bg = NULL;
struct btrfs_ordered_extent *ordered;
struct btrfs_key found_key;
struct btrfs_file_extent_item *fi;
@ -2003,8 +2002,6 @@ static noinline int run_delalloc_nocow(struct btrfs_inode *inode,
int extent_type;
bool is_prealloc;
nocow = false;
ret = btrfs_lookup_file_extent(NULL, root, path, ino,
cur_offset, 0);
if (ret < 0)
@ -2063,7 +2060,7 @@ next_slot:
if (found_key.offset > cur_offset) {
extent_end = found_key.offset;
extent_type = 0;
goto out_check;
goto must_cow;
}
/*
@ -2096,18 +2093,19 @@ next_slot:
if (ret < 0)
goto error;
if (ret == 0)
goto out_check;
goto must_cow;
ret = 0;
bg = btrfs_inc_nocow_writers(fs_info, nocow_args.disk_bytenr);
if (bg)
nocow = true;
out_check:
/*
* If nocow is false then record the beginning of the range
* that needs to be COWed
*/
if (!nocow) {
nocow_bg = btrfs_inc_nocow_writers(fs_info, nocow_args.disk_bytenr);
if (!nocow_bg) {
must_cow:
/*
* If we can't perform NOCOW writeback for the range,
* then record the beginning of the range that needs to
* be COWed. It will be written out before the next
* NOCOW range if we find one, or when exiting this
* loop.
*/
if (cow_start == (u64)-1)
cow_start = cur_offset;
cur_offset = extent_end;
@ -2128,8 +2126,10 @@ out_check:
ret = fallback_to_cow(inode, locked_page,
cow_start, found_key.offset - 1);
cow_start = (u64)-1;
if (ret)
if (ret) {
btrfs_dec_nocow_writers(nocow_bg);
goto error;
}
}
nocow_end = cur_offset + nocow_args.num_bytes - 1;
@ -2146,6 +2146,7 @@ out_check:
ram_bytes, BTRFS_COMPRESS_NONE,
BTRFS_ORDERED_PREALLOC);
if (IS_ERR(em)) {
btrfs_dec_nocow_writers(nocow_bg);
ret = PTR_ERR(em);
goto error;
}
@ -2159,6 +2160,7 @@ out_check:
? (1 << BTRFS_ORDERED_PREALLOC)
: (1 << BTRFS_ORDERED_NOCOW),
BTRFS_COMPRESS_NONE);
btrfs_dec_nocow_writers(nocow_bg);
if (IS_ERR(ordered)) {
if (is_prealloc) {
btrfs_drop_extent_map_range(inode, cur_offset,
@ -2168,11 +2170,6 @@ out_check:
goto error;
}
if (nocow) {
btrfs_dec_nocow_writers(bg);
nocow = false;
}
if (btrfs_is_data_reloc_root(root))
/*
* Error handled later, as we must prevent
@ -2213,10 +2210,10 @@ out_check:
goto error;
}
error:
if (nocow)
btrfs_dec_nocow_writers(bg);
btrfs_free_path(path);
return 0;
error:
/*
* If an error happened while a COW region is outstanding, cur_offset
* needs to be reset to cow_start to ensure the COW region is unlocked
@ -2224,7 +2221,7 @@ error:
*/
if (cow_start != (u64)-1)
cur_offset = cow_start;
if (ret && cur_offset < end)
if (cur_offset < end)
extent_clear_unlock_delalloc(inode, cur_offset, end,
locked_page, EXTENT_LOCKED |
EXTENT_DELALLOC | EXTENT_DEFRAG |