[PATCH 5.18 1020/1095] btrfs: replace BTRFS_MAX_EXTENT_SIZE with fs_info->max_extent_size

From: Greg Kroah-Hartman
Date: Mon Aug 15 2022 - 19:28:44 EST

From: Naohiro Aota <naohiro.aota@xxxxxxx>

[ Upstream commit f7b12a62f008a3041f42f2426983e59a6a0a3c59 ]

On zoned filesystem, data write out is limited by max_zone_append_size,
and a large ordered extent is split according the size of a bio. OTOH,
the number of extents to be written is calculated using
BTRFS_MAX_EXTENT_SIZE, and that estimated number is used to reserve the
metadata bytes to update and/or create the metadata items.

The metadata reservation is done at e.g, btrfs_buffered_write() and then
released according to the estimation changes. Thus, if the number of extent
increases massively, the reserved metadata can run out.

The increase of the number of extents easily occurs on zoned filesystem
if BTRFS_MAX_EXTENT_SIZE > max_zone_append_size. And, it causes the
following warning on a small RAM environment with disabling metadata
over-commit (in the following patch).

[75721.498492] ------------[ cut here ]------------
[75721.505624] BTRFS: block rsv 1 returned -28
[75721.512230] WARNING: CPU: 24 PID: 2327559 at fs/btrfs/block-rsv.c:537 btrfs_use_block_rsv+0x560/0x760 [btrfs]
[75721.581854] CPU: 24 PID: 2327559 Comm: kworker/u64:10 Kdump: loaded Tainted: G W 5.18.0-rc2-BTRFS-ZNS+ #109
[75721.597200] Hardware name: Supermicro Super Server/H12SSL-NT, BIOS 2.0 02/22/2021
[75721.607310] Workqueue: btrfs-endio-write btrfs_work_helper [btrfs]
[75721.616209] RIP: 0010:btrfs_use_block_rsv+0x560/0x760 [btrfs]
[75721.646649] RSP: 0018:ffffc9000fbdf3e0 EFLAGS: 00010286
[75721.654126] RAX: 0000000000000000 RBX: 0000000000004000 RCX: 0000000000000000
[75721.663524] RDX: 0000000000000004 RSI: 0000000000000008 RDI: fffff52001f7be6e
[75721.672921] RBP: ffffc9000fbdf420 R08: 0000000000000001 R09: ffff889f8d1fc6c7
[75721.682493] R10: ffffed13f1a3f8d8 R11: 0000000000000001 R12: ffff88980a3c0e28
[75721.692284] R13: ffff889b66590000 R14: ffff88980a3c0e40 R15: ffff88980a3c0e8a
[75721.701878] FS: 0000000000000000(0000) GS:ffff889f8d000000(0000) knlGS:0000000000000000
[75721.712601] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[75721.720726] CR2: 000055d12e05c018 CR3: 0000800193594000 CR4: 0000000000350ee0
[75721.730499] Call Trace:
[75721.735166] <TASK>
[75721.739886] btrfs_alloc_tree_block+0x1e1/0x1100 [btrfs]
[75721.747545] ? btrfs_alloc_logged_file_extent+0x550/0x550 [btrfs]
[75721.756145] ? btrfs_get_32+0xea/0x2d0 [btrfs]
[75721.762852] ? btrfs_get_32+0xea/0x2d0 [btrfs]
[75721.769520] ? push_leaf_left+0x420/0x620 [btrfs]
[75721.776431] ? memcpy+0x4e/0x60
[75721.781931] split_leaf+0x433/0x12d0 [btrfs]
[75721.788392] ? btrfs_get_token_32+0x580/0x580 [btrfs]
[75721.795636] ? push_for_double_split.isra.0+0x420/0x420 [btrfs]
[75721.803759] ? leaf_space_used+0x15d/0x1a0 [btrfs]
[75721.811156] btrfs_search_slot+0x1bc3/0x2790 [btrfs]
[75721.818300] ? lock_downgrade+0x7c0/0x7c0
[75721.824411] ? free_extent_buffer.part.0+0x107/0x200 [btrfs]
[75721.832456] ? split_leaf+0x12d0/0x12d0 [btrfs]
[75721.839149] ? free_extent_buffer.part.0+0x14f/0x200 [btrfs]
[75721.846945] ? free_extent_buffer+0x13/0x20 [btrfs]
[75721.853960] ? btrfs_release_path+0x4b/0x190 [btrfs]
[75721.861429] btrfs_csum_file_blocks+0x85c/0x1500 [btrfs]
[75721.869313] ? rcu_read_lock_sched_held+0x16/0x80
[75721.876085] ? lock_release+0x552/0xf80
[75721.881957] ? btrfs_del_csums+0x8c0/0x8c0 [btrfs]
[75721.888886] ? __kasan_check_write+0x14/0x20
[75721.895152] ? do_raw_read_unlock+0x44/0x80
[75721.901323] ? _raw_write_lock_irq+0x60/0x80
[75721.907983] ? btrfs_global_root+0xb9/0xe0 [btrfs]
[75721.915166] ? btrfs_csum_root+0x12b/0x180 [btrfs]
[75721.921918] ? btrfs_get_global_root+0x820/0x820 [btrfs]
[75721.929166] ? _raw_write_unlock+0x23/0x40
[75721.935116] ? unpin_extent_cache+0x1e3/0x390 [btrfs]
[75721.942041] btrfs_finish_ordered_io.isra.0+0xa0c/0x1dc0 [btrfs]
[75721.949906] ? try_to_wake_up+0x30/0x14a0
[75721.955700] ? btrfs_unlink_subvol+0xda0/0xda0 [btrfs]
[75721.962661] ? rcu_read_lock_sched_held+0x16/0x80
[75721.969111] ? lock_acquire+0x41b/0x4c0
[75721.974982] finish_ordered_fn+0x15/0x20 [btrfs]
[75721.981639] btrfs_work_helper+0x1af/0xa80 [btrfs]
[75721.988184] ? _raw_spin_unlock_irq+0x28/0x50
[75721.994643] process_one_work+0x815/0x1460
[75722.000444] ? pwq_dec_nr_in_flight+0x250/0x250
[75722.006643] ? do_raw_spin_trylock+0xbb/0x190
[75722.013086] worker_thread+0x59a/0xeb0
[75722.018511] kthread+0x2ac/0x360
[75722.023428] ? process_one_work+0x1460/0x1460
[75722.029431] ? kthread_complete_and_exit+0x30/0x30
[75722.036044] ret_from_fork+0x22/0x30
[75722.041255] </TASK>
[75722.045047] irq event stamp: 0
[75722.049703] hardirqs last enabled at (0): [<0000000000000000>] 0x0
[75722.057610] hardirqs last disabled at (0): [<ffffffff8118a94a>] copy_process+0x1c1a/0x66b0
[75722.067533] softirqs last enabled at (0): [<ffffffff8118a989>] copy_process+0x1c59/0x66b0
[75722.077423] softirqs last disabled at (0): [<0000000000000000>] 0x0
[75722.085335] ---[ end trace 0000000000000000 ]---

To fix the estimation, we need to introduce fs_info->max_extent_size to
replace BTRFS_MAX_EXTENT_SIZE, which allow setting the different size for
regular vs zoned filesystem.

Set fs_info->max_extent_size to BTRFS_MAX_EXTENT_SIZE by default. On zoned
filesystem, it is set to fs_info->max_zone_append_size.

CC: stable@xxxxxxxxxxxxxxx # 5.12+
Fixes: d8e3fb106f39 ("btrfs: zoned: use ZONE_APPEND write for zoned mode")
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@xxxxxxx>
Signed-off-by: Naohiro Aota <naohiro.aota@xxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/btrfs/ctree.h | 6 ++++++
fs/btrfs/disk-io.c | 2 ++
fs/btrfs/extent_io.c | 4 +++-
fs/btrfs/inode.c | 6 ++++--
fs/btrfs/zoned.c | 5 ++++-
5 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 1c377bcfe787..97f5a3d320ff 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1032,6 +1032,12 @@ struct btrfs_fs_info {
u32 csums_per_leaf;
u32 stripesize;

+ /*
+ * Maximum size of an extent. BTRFS_MAX_EXTENT_SIZE on regular
+ * filesystem, on zoned it depends on the device constraints.
+ */
+ u64 max_extent_size;
+
/* Block groups and devices containing active swapfiles. */
spinlock_t swapfile_pins_lock;
struct rb_root swapfile_pins;
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 34cd57d799e4..bf5c6ac67e87 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3246,6 +3246,8 @@ void btrfs_init_fs_info(struct btrfs_fs_info *fs_info)
fs_info->sectorsize_bits = ilog2(4096);
fs_info->stripesize = 4096;

+ fs_info->max_extent_size = BTRFS_MAX_EXTENT_SIZE;
+
spin_lock_init(&fs_info->swapfile_pins_lock);
fs_info->swapfile_pins = RB_ROOT;

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 68ddd90685d9..bfc7d5b31156 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -1992,10 +1992,12 @@ noinline_for_stack bool find_lock_delalloc_range(struct inode *inode,
struct page *locked_page, u64 *start,
u64 *end)
{
+ struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
const u64 orig_start = *start;
const u64 orig_end = *end;
- u64 max_bytes = BTRFS_MAX_EXTENT_SIZE;
+ /* The sanity tests may not set a valid fs_info. */
+ u64 max_bytes = fs_info ? fs_info->max_extent_size : BTRFS_MAX_EXTENT_SIZE;
u64 delalloc_start;
u64 delalloc_end;
bool found;
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 1e404476fe6a..c50288d90c66 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2102,6 +2102,7 @@ int btrfs_run_delalloc_range(struct btrfs_inode *inode, struct page *locked_page
void btrfs_split_delalloc_extent(struct inode *inode,
struct extent_state *orig, u64 split)
{
+ struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
u64 size;

/* not delalloc, ignore it */
@@ -2109,7 +2110,7 @@ void btrfs_split_delalloc_extent(struct inode *inode,
return;

size = orig->end - orig->start + 1;
- if (size > BTRFS_MAX_EXTENT_SIZE) {
+ if (size > fs_info->max_extent_size) {
u32 num_extents;
u64 new_size;

@@ -2138,6 +2139,7 @@ void btrfs_split_delalloc_extent(struct inode *inode,
void btrfs_merge_delalloc_extent(struct inode *inode, struct extent_state *new,
struct extent_state *other)
{
+ struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
u64 new_size, old_size;
u32 num_extents;

@@ -2151,7 +2153,7 @@ void btrfs_merge_delalloc_extent(struct inode *inode, struct extent_state *new,
new_size = other->end - new->start + 1;

/* we're not bigger than the max, unreserve the space and go */
- if (new_size <= BTRFS_MAX_EXTENT_SIZE) {
+ if (new_size <= fs_info->max_extent_size) {
spin_lock(&BTRFS_I(inode)->lock);
btrfs_mod_outstanding_extents(BTRFS_I(inode), -1);
spin_unlock(&BTRFS_I(inode)->lock);
diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index 1d5b9308f5ef..a0bf2c20fa61 100644
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -731,8 +731,11 @@ int btrfs_check_zoned_mode(struct btrfs_fs_info *fs_info)
}

fs_info->zone_size = zone_size;
- fs_info->max_zone_append_size = max_zone_append_size;
+ fs_info->max_zone_append_size = ALIGN_DOWN(max_zone_append_size,
+ fs_info->sectorsize);
fs_info->fs_devices->chunk_alloc_policy = BTRFS_CHUNK_ALLOC_ZONED;
+ if (fs_info->max_zone_append_size < fs_info->max_extent_size)
+ fs_info->max_extent_size = fs_info->max_zone_append_size;

/*
* Check mount options here, because we might change fs_info->zoned
--
2.35.1