This is a note to let you know that I've just added the patch titled btrfs: zoned: write out partially allocated region to the 5.18-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: btrfs-zoned-write-out-partially-allocated-region.patch and it can be found in the queue-5.18 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit e3d143c47bd2fd49137af62c599571f2ab7620d6 Author: Naohiro Aota <naohiro.aota@xxxxxxx> Date: Sat Jul 9 08:18:49 2022 +0900 btrfs: zoned: write out partially allocated region [ Upstream commit 898793d992c23dac6126a6a94ad893eae1a2c9df ] cow_file_range() works in an all-or-nothing way: if it fails to allocate an extent for a part of the given region, it gives up all the region including the successfully allocated parts. On cow_file_range(), run_delalloc_zoned() writes data for the region only when it successfully allocate all the region. This all-or-nothing allocation and write-out are problematic when available space in all the block groups are get tight with the active zone restriction. btrfs_reserve_extent() try hard to utilize the left space in the active block groups and gives up finally and fails with -ENOSPC. However, if we send IOs for the successfully allocated region, we can finish a zone and can continue on the rest of the allocation on a newly allocated block group. This patch implements the partial write-out for run_delalloc_zoned(). With this patch applied, cow_file_range() returns -EAGAIN to tell the caller to do something to progress the further allocation, and tells the successfully allocated region with done_offset. Furthermore, the zoned extent allocator returns -EAGAIN to tell cow_file_range() going back to the caller side. Actually, we still need to wait for an IO to complete to continue the allocation. The next patch implements that part. CC: stable@xxxxxxxxxxxxxxx # 5.16+ Fixes: afba2bc036b0 ("btrfs: zoned: implement active zone tracking") Signed-off-by: Naohiro Aota <naohiro.aota@xxxxxxx> Signed-off-by: David Sterba <dsterba@xxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 56185541e188..eee68a6f2be7 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -4015,6 +4015,16 @@ static int can_allocate_chunk_zoned(struct btrfs_fs_info *fs_info, if (ffe_ctl->max_extent_size >= ffe_ctl->min_alloc_size) return -ENOSPC; + /* + * Even min_alloc_size is not left in any block groups. Since we cannot + * activate a new block group, allocating it may not help. Let's tell a + * caller to try again and hope it progress something by writing some + * parts of the region. That is only possible for data block groups, + * where a part of the region can be written. + */ + if (ffe_ctl->flags & BTRFS_BLOCK_GROUP_DATA) + return -EAGAIN; + /* * We cannot activate a new block group and no enough space left in any * block groups. So, allocating a new block group may not help. But, diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index c50288d90c66..9753fc47e488 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -92,7 +92,8 @@ static int btrfs_finish_ordered_io(struct btrfs_ordered_extent *ordered_extent); static noinline int cow_file_range(struct btrfs_inode *inode, struct page *locked_page, u64 start, u64 end, int *page_started, - unsigned long *nr_written, int unlock); + unsigned long *nr_written, int unlock, + u64 *done_offset); static struct extent_map *create_io_em(struct btrfs_inode *inode, u64 start, u64 len, u64 orig_start, u64 block_start, u64 block_len, u64 orig_block_len, @@ -884,7 +885,7 @@ static int submit_uncompressed_range(struct btrfs_inode *inode, * can directly submit them without interruption. */ ret = cow_file_range(inode, locked_page, start, end, &page_started, - &nr_written, 0); + &nr_written, 0, NULL); /* Inline extent inserted, page gets unlocked and everything is done */ if (page_started) { ret = 0; @@ -1133,7 +1134,8 @@ static u64 get_extent_allocation_hint(struct btrfs_inode *inode, u64 start, static noinline int cow_file_range(struct btrfs_inode *inode, struct page *locked_page, u64 start, u64 end, int *page_started, - unsigned long *nr_written, int unlock) + unsigned long *nr_written, int unlock, + u64 *done_offset) { struct btrfs_root *root = inode->root; struct btrfs_fs_info *fs_info = root->fs_info; @@ -1326,6 +1328,21 @@ static noinline int cow_file_range(struct btrfs_inode *inode, btrfs_dec_block_group_reservations(fs_info, ins.objectid); btrfs_free_reserved_extent(fs_info, ins.objectid, ins.offset, 1); out_unlock: + /* + * If done_offset is non-NULL and ret == -EAGAIN, we expect the + * caller to write out the successfully allocated region and retry. + */ + if (done_offset && ret == -EAGAIN) { + if (orig_start < start) + *done_offset = start - 1; + else + *done_offset = start; + return ret; + } else if (ret == -EAGAIN) { + /* Convert to -ENOSPC since the caller cannot retry. */ + ret = -ENOSPC; + } + /* * Now, we have three regions to clean up: * @@ -1571,19 +1588,37 @@ static noinline int run_delalloc_zoned(struct btrfs_inode *inode, u64 end, int *page_started, unsigned long *nr_written) { + u64 done_offset = end; int ret; + bool locked_page_done = false; - ret = cow_file_range(inode, locked_page, start, end, page_started, - nr_written, 0); - if (ret) - return ret; + while (start <= end) { + ret = cow_file_range(inode, locked_page, start, end, page_started, + nr_written, 0, &done_offset); + if (ret && ret != -EAGAIN) + return ret; - if (*page_started) - return 0; + if (*page_started) { + ASSERT(ret == 0); + return 0; + } + + if (ret == 0) + done_offset = end; + + if (done_offset == start) + return -ENOSPC; + + if (!locked_page_done) { + __set_page_dirty_nobuffers(locked_page); + account_page_redirty(locked_page); + } + locked_page_done = true; + extent_write_locked_range(&inode->vfs_inode, start, done_offset); + + start = done_offset + 1; + } - __set_page_dirty_nobuffers(locked_page); - account_page_redirty(locked_page); - extent_write_locked_range(&inode->vfs_inode, start, end); *page_started = 1; return 0; @@ -1675,7 +1710,7 @@ static int fallback_to_cow(struct btrfs_inode *inode, struct page *locked_page, } return cow_file_range(inode, locked_page, start, end, page_started, - nr_written, 1); + nr_written, 1, NULL); } /* @@ -2086,7 +2121,7 @@ int btrfs_run_delalloc_range(struct btrfs_inode *inode, struct page *locked_page page_started, nr_written); else ret = cow_file_range(inode, locked_page, start, end, - page_started, nr_written, 1); + 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,