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Message-ID: <4d0603d4-1503-4e8f-bfe2-ed205b598072@gmx.com>
Date: Wed, 30 Oct 2024 13:31:15 +1030
From: Qu Wenruo <quwenruo.btrfs@....com>
To: iamhswang@...il.com, linux-btrfs@...r.kernel.org
Cc: clm@...com, josef@...icpanda.com, dsterba@...e.com, wqu@...e.com,
boris@....io, linux-kernel@...r.kernel.org,
Haisu Wang <haisuwang@...cent.com>
Subject: Re: [PATCH 2/2] btrfs: simplify regions mark and keep start unchanged
in err handling
在 2024/10/25 17:24, iamhswang@...il.com 写道:
> From: Haisu Wang <haisuwang@...cent.com>
>
> Simplify the regions mark by using cur_alloc_size only to present
> the reserved but may failed to alloced extent. Remove the ram_size
> as well since it is always consistent to the cur_alloc_size in the
> context. Advanced the start mark in normal path until extent succeed
> alloced and keep the start unchanged in error handling path.
>
> PASSed the fstest generic/475 test for a hundred times with quota
> enabled. And a modified generic/475 test by removing the sleep time
> for a hundred times. About one tenth of the tests do enter the error
> handling path due to fail to reserve extent.
>
Although this patch is already merged into for-next, it looks like the
next patch will again change the error handling, mostly render the this
one useless:
https://lore.kernel.org/linux-btrfs/2a0925f0264daf90741ed0a7ba7ed4b4888cf778.1728725060.git.wqu@suse.com/
The newer patch will change the error handling to a simpler one, so
instead of 3 regions, there will be only 2.
There will be no change needed from your side, I will update my patches
to solve the conflicts, just in case if you find the error handling is
different in the future.
Thanks,
Qu
> Suggested-by: Qu Wenruo <wqu@...e.com>
> Signed-off-by: Haisu Wang <haisuwang@...cent.com>
> ---
> fs/btrfs/inode.c | 32 ++++++++++++++------------------
> 1 file changed, 14 insertions(+), 18 deletions(-)
>
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 3646734a7e59..7e67a6d50be2 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -1359,7 +1359,6 @@ static noinline int cow_file_range(struct btrfs_inode *inode,
> u64 alloc_hint = 0;
> u64 orig_start = start;
> u64 num_bytes;
> - unsigned long ram_size;
> u64 cur_alloc_size = 0;
> u64 min_alloc_size;
> u64 blocksize = fs_info->sectorsize;
> @@ -1367,7 +1366,6 @@ static noinline int cow_file_range(struct btrfs_inode *inode,
> struct extent_map *em;
> unsigned clear_bits;
> unsigned long page_ops;
> - bool extent_reserved = false;
> int ret = 0;
>
> if (btrfs_is_free_space_inode(inode)) {
> @@ -1421,8 +1419,7 @@ static noinline int cow_file_range(struct btrfs_inode *inode,
> struct btrfs_ordered_extent *ordered;
> struct btrfs_file_extent file_extent;
>
> - cur_alloc_size = num_bytes;
> - ret = btrfs_reserve_extent(root, cur_alloc_size, cur_alloc_size,
> + ret = btrfs_reserve_extent(root, num_bytes, num_bytes,
> min_alloc_size, 0, alloc_hint,
> &ins, 1, 1);
> if (ret == -EAGAIN) {
> @@ -1453,9 +1450,7 @@ static noinline int cow_file_range(struct btrfs_inode *inode,
> if (ret < 0)
> goto out_unlock;
> cur_alloc_size = ins.offset;
> - extent_reserved = true;
>
> - ram_size = ins.offset;
> file_extent.disk_bytenr = ins.objectid;
> file_extent.disk_num_bytes = ins.offset;
> file_extent.num_bytes = ins.offset;
> @@ -1463,14 +1458,14 @@ static noinline int cow_file_range(struct btrfs_inode *inode,
> file_extent.offset = 0;
> file_extent.compression = BTRFS_COMPRESS_NONE;
>
> - lock_extent(&inode->io_tree, start, start + ram_size - 1,
> + lock_extent(&inode->io_tree, start, start + cur_alloc_size - 1,
> &cached);
>
> em = btrfs_create_io_em(inode, start, &file_extent,
> BTRFS_ORDERED_REGULAR);
> if (IS_ERR(em)) {
> unlock_extent(&inode->io_tree, start,
> - start + ram_size - 1, &cached);
> + start + cur_alloc_size - 1, &cached);
> ret = PTR_ERR(em);
> goto out_reserve;
> }
> @@ -1480,7 +1475,7 @@ static noinline int cow_file_range(struct btrfs_inode *inode,
> 1 << BTRFS_ORDERED_REGULAR);
> if (IS_ERR(ordered)) {
> unlock_extent(&inode->io_tree, start,
> - start + ram_size - 1, &cached);
> + start + cur_alloc_size - 1, &cached);
> ret = PTR_ERR(ordered);
> goto out_drop_extent_cache;
> }
> @@ -1501,7 +1496,7 @@ static noinline int cow_file_range(struct btrfs_inode *inode,
> */
> if (ret)
> btrfs_drop_extent_map_range(inode, start,
> - start + ram_size - 1,
> + start + cur_alloc_size - 1,
> false);
> }
> btrfs_put_ordered_extent(ordered);
> @@ -1519,7 +1514,7 @@ static noinline int cow_file_range(struct btrfs_inode *inode,
> page_ops = (keep_locked ? 0 : PAGE_UNLOCK);
> page_ops |= PAGE_SET_ORDERED;
>
> - extent_clear_unlock_delalloc(inode, start, start + ram_size - 1,
> + extent_clear_unlock_delalloc(inode, start, start + cur_alloc_size - 1,
> locked_folio, &cached,
> EXTENT_LOCKED | EXTENT_DELALLOC,
> page_ops);
> @@ -1529,7 +1524,7 @@ static noinline int cow_file_range(struct btrfs_inode *inode,
> num_bytes -= cur_alloc_size;
> alloc_hint = ins.objectid + ins.offset;
> start += cur_alloc_size;
> - extent_reserved = false;
> + cur_alloc_size = 0;
>
> /*
> * btrfs_reloc_clone_csums() error, since start is increased
> @@ -1545,7 +1540,7 @@ static noinline int cow_file_range(struct btrfs_inode *inode,
> return ret;
>
> out_drop_extent_cache:
> - btrfs_drop_extent_map_range(inode, start, start + ram_size - 1, false);
> + btrfs_drop_extent_map_range(inode, start, start + cur_alloc_size - 1, false);
> out_reserve:
> btrfs_dec_block_group_reservations(fs_info, ins.objectid);
> btrfs_free_reserved_extent(fs_info, ins.objectid, ins.offset, 1);
> @@ -1599,13 +1594,12 @@ static noinline int cow_file_range(struct btrfs_inode *inode,
> * to decrement again the data space_info's bytes_may_use counter,
> * therefore we do not pass it the flag EXTENT_CLEAR_DATA_RESV.
> */
> - if (extent_reserved) {
> + if (cur_alloc_size) {
> extent_clear_unlock_delalloc(inode, start,
> start + cur_alloc_size - 1,
> locked_folio, &cached, clear_bits,
> page_ops);
> btrfs_qgroup_free_data(inode, NULL, start, cur_alloc_size, NULL);
> - start += cur_alloc_size;
> }
>
> /*
> @@ -1614,11 +1608,13 @@ static noinline int cow_file_range(struct btrfs_inode *inode,
> * space_info's bytes_may_use counter, reserved in
> * btrfs_check_data_free_space().
> */
> - if (start < end) {
> + if (start + cur_alloc_size < end) {
> clear_bits |= EXTENT_CLEAR_DATA_RESV;
> - extent_clear_unlock_delalloc(inode, start, end, locked_folio,
> + extent_clear_unlock_delalloc(inode, start + cur_alloc_size,
> + end, locked_folio,
> &cached, clear_bits, page_ops);
> - btrfs_qgroup_free_data(inode, NULL, start, end - start + 1, NULL);
> + btrfs_qgroup_free_data(inode, NULL, start + cur_alloc_size,
> + end - start - cur_alloc_size + 1, NULL);
> }
> return ret;
> }
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