| Message ID | 99be1657b5273f3a9d24e53f6be9303b381a51eb.1713363472.git.josef@toxicpanda.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | btrfs: restrain lock extent usage during writeback | expand |
On 17.04.24 16:36, Josef Bacik wrote: > We currently don't lock the extent when we're doing a > cow_file_range_inline() for a compressed extent. This isn't a problem > necessarily, but it's inconsistent with the rest of our usage of > cow_file_range_inline(). This also leads to some extra weird logic > around whether the extent is locked or not. Fix this to lock the extent > before calling cow_file_range_inline() in compression to make it > consistent with the rest of the inline users. In future patches this > will be pushed down into the cow_file_range_inline() helper, so we're > fine with the quick and dirty locking here. This patch exists to make > the behavior change obvious. But in btrfs_do_encoded_write() we're still not locking the compressed extents and call __cow_file_range_inline(). This deviation should at least be documented here.
On Wed, Apr 17, 2024 at 04:29:52PM +0000, Johannes Thumshirn wrote: > On 17.04.24 16:36, Josef Bacik wrote: > > We currently don't lock the extent when we're doing a > > cow_file_range_inline() for a compressed extent. This isn't a problem > > necessarily, but it's inconsistent with the rest of our usage of > > cow_file_range_inline(). This also leads to some extra weird logic > > around whether the extent is locked or not. Fix this to lock the extent > > before calling cow_file_range_inline() in compression to make it > > consistent with the rest of the inline users. In future patches this > > will be pushed down into the cow_file_range_inline() helper, so we're > > fine with the quick and dirty locking here. This patch exists to make > > the behavior change obvious. > > But in btrfs_do_encoded_write() we're still not locking the compressed > extents and call __cow_file_range_inline(). We are though, the extent is locked the entire operation during encoded writes. Thanks, Josef
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 6fd866a793bb..ba74476ac423 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -742,10 +742,10 @@ static noinline int cow_file_range_inline(struct btrfs_inode *inode, u64 offset, size_t compressed_size, int compress_type, struct folio *compressed_folio, - bool update_i_size, bool locked) + bool update_i_size) { unsigned long clear_flags = EXTENT_DELALLOC | EXTENT_DELALLOC_NEW | - EXTENT_DEFRAG | EXTENT_DO_ACCOUNTING; + EXTENT_DEFRAG | EXTENT_DO_ACCOUNTING | EXTENT_LOCKED; u64 size = min_t(u64, i_size_read(&inode->vfs_inode), end + 1); int ret; @@ -755,9 +755,6 @@ static noinline int cow_file_range_inline(struct btrfs_inode *inode, u64 offset, if (ret > 0) return ret; - if (locked) - clear_flags |= EXTENT_LOCKED; - extent_clear_unlock_delalloc(inode, offset, end, NULL, clear_flags, PAGE_UNLOCK | PAGE_START_WRITEBACK | PAGE_END_WRITEBACK); @@ -1031,18 +1028,19 @@ static void compress_file_range(struct btrfs_work *work) * Check cow_file_range() for why we don't even try to create inline * extent for the subpage case. */ + lock_extent(&inode->io_tree, start, end, NULL); if (total_in < actual_end) ret = cow_file_range_inline(inode, start, end, 0, - BTRFS_COMPRESS_NONE, NULL, false, - false); + BTRFS_COMPRESS_NONE, NULL, false); else ret = cow_file_range_inline(inode, start, end, total_compressed, - compress_type, folios[0], false, false); + compress_type, folios[0], false); if (ret <= 0) { if (ret < 0) mapping_set_error(mapping, -EIO); goto free_pages; } + unlock_extent(&inode->io_tree, start, end, NULL); /* * We aren't doing an inline extent. Round the compressed size up to a @@ -1352,8 +1350,7 @@ static noinline int cow_file_range(struct btrfs_inode *inode, if (!no_inline) { /* lets try to make an inline extent */ ret = cow_file_range_inline(inode, start, end, 0, - BTRFS_COMPRESS_NONE, NULL, false, - true); + BTRFS_COMPRESS_NONE, NULL, false); if (ret <= 0) { /* * We succeeded, return 1 so the caller knows we're done
We currently don't lock the extent when we're doing a cow_file_range_inline() for a compressed extent. This isn't a problem necessarily, but it's inconsistent with the rest of our usage of cow_file_range_inline(). This also leads to some extra weird logic around whether the extent is locked or not. Fix this to lock the extent before calling cow_file_range_inline() in compression to make it consistent with the rest of the inline users. In future patches this will be pushed down into the cow_file_range_inline() helper, so we're fine with the quick and dirty locking here. This patch exists to make the behavior change obvious. Signed-off-by: Josef Bacik <josef@toxicpanda.com> --- fs/btrfs/inode.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-)