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btrfs: don't fail writeback when allocating the compression context fails

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If cow_file_range_async fails to allocate the asynchronous writeback
context, it currently returns an error and entirely fails the writeback.
This is not a good idea as a writeback failure is a non-temporary error
condition that will make the file system unusable.  Just fall back to
synchronous uncompressed writeback instead.  This requires us to delay
setting the BTRFS_INODE_HAS_ASYNC_EXTENT flag until we've committed to
the async writeback.

The compression checks INODE_NOCOMPRESS and FORCE_COMPRESS are moved
from cow_file_range_async to the preceding checks btrfs_run_delalloc_range().

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Christoph Hellwig 2023-05-31 08:04:54 +02:00 committed by David Sterba
parent 57201dddd6
commit 973fb26e81
1 changed files with 28 additions and 46 deletions
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74
fs/btrfs/inode.c
View file

@ -1720,58 +1720,36 @@ static noinline void async_cow_free(struct btrfs_work *work)
kvfree(async_cow);
}
static int cow_file_range_async(struct btrfs_inode *inode,
struct writeback_control *wbc,
struct page *locked_page,
u64 start, u64 end, int *page_started,
unsigned long *nr_written)
static bool cow_file_range_async(struct btrfs_inode *inode,
struct writeback_control *wbc,
struct page *locked_page,
u64 start, u64 end, int *page_started,
unsigned long *nr_written)
{
struct btrfs_fs_info *fs_info = inode->root->fs_info;
struct cgroup_subsys_state *blkcg_css = wbc_blkcg_css(wbc);
struct async_cow *ctx;
struct async_chunk *async_chunk;
unsigned long nr_pages;
u64 cur_end;
u64 num_chunks = DIV_ROUND_UP(end - start, SZ_512K);
int i;
bool should_compress;
unsigned nofs_flag;
const blk_opf_t write_flags = wbc_to_write_flags(wbc);
unlock_extent(&inode->io_tree, start, end, NULL);
if (inode->flags & BTRFS_INODE_NOCOMPRESS &&
!btrfs_test_opt(fs_info, FORCE_COMPRESS)) {
num_chunks = 1;
should_compress = false;
} else {
should_compress = true;
}
nofs_flag = memalloc_nofs_save();
ctx = kvmalloc(struct_size(ctx, chunks, num_chunks), GFP_KERNEL);
memalloc_nofs_restore(nofs_flag);
if (!ctx)
return false;
if (!ctx) {
unsigned clear_bits = EXTENT_LOCKED | EXTENT_DELALLOC |
EXTENT_DELALLOC_NEW | EXTENT_DEFRAG |
EXTENT_DO_ACCOUNTING;
unsigned long page_ops = PAGE_UNLOCK | PAGE_START_WRITEBACK |
PAGE_END_WRITEBACK | PAGE_SET_ERROR;
extent_clear_unlock_delalloc(inode, start, end, locked_page,
clear_bits, page_ops);
return -ENOMEM;
}
unlock_extent(&inode->io_tree, start, end, NULL);
set_bit(BTRFS_INODE_HAS_ASYNC_EXTENT, &inode->runtime_flags);
async_chunk = ctx->chunks;
atomic_set(&ctx->num_chunks, num_chunks);
for (i = 0; i < num_chunks; i++) {
if (should_compress)
cur_end = min(end, start + SZ_512K - 1);
else
cur_end = end;
u64 cur_end = min(end, start + SZ_512K - 1);
/*
* igrab is called higher up in the call chain, take only the
@ -1832,7 +1810,7 @@ static int cow_file_range_async(struct btrfs_inode *inode,
start = cur_end + 1;
}
*page_started = 1;
return 0;
return true;
}
static noinline int run_delalloc_zoned(struct btrfs_inode *inode,
@ -2413,7 +2391,7 @@ int btrfs_run_delalloc_range(struct btrfs_inode *inode, struct page *locked_page
u64 start, u64 end, int *page_started, unsigned long *nr_written,
struct writeback_control *wbc)
{
int ret;
int ret = 0;
const bool zoned = btrfs_is_zoned(inode->root->fs_info);
/*
@ -2434,19 +2412,23 @@ int btrfs_run_delalloc_range(struct btrfs_inode *inode, struct page *locked_page
ASSERT(!zoned || btrfs_is_data_reloc_root(inode->root));
ret = run_delalloc_nocow(inode, locked_page, start, end,
page_started, nr_written);
} else if (!btrfs_inode_can_compress(inode) ||
!inode_need_compress(inode, start, end)) {
if (zoned)
ret = run_delalloc_zoned(inode, locked_page, start, end,
page_started, nr_written);
else
ret = cow_file_range(inode, locked_page, start, end,
page_started, nr_written, 1, NULL);
} else {
set_bit(BTRFS_INODE_HAS_ASYNC_EXTENT, &inode->runtime_flags);
ret = cow_file_range_async(inode, wbc, locked_page, start, end,
page_started, nr_written);
goto out;
}
if (btrfs_inode_can_compress(inode) &&
inode_need_compress(inode, start, end) &&
cow_file_range_async(inode, wbc, locked_page, start,
end, page_started, nr_written))
goto out;
if (zoned)
ret = run_delalloc_zoned(inode, locked_page, start, end,
page_started, nr_written);
else
ret = cow_file_range(inode, locked_page, start, end,
page_started, nr_written, 1, NULL);
out:
ASSERT(ret <= 0);
if (ret)
btrfs_cleanup_ordered_extents(inode, locked_page, start,