On zoned btrfs, 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 btrfs 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]
[75721.524407] Modules linked in: btrfs null_blk blake2b_generic xor
raid6_pq loop dm_flakey dm_mod algif_hash af_alg veth xt_nat xt_conntrack
xt_MASQUERADE nf_conntrack_netlink nfnetlink xt_addrtype iptable_filter
iptable_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 bpfilter
br_netfilter bridge stp llc overlay sunrpc ext4 mbcache jbd2 rapl ipmi_ssif
bfq k10temp i2c_piix4 ipmi_si ipmi_devintf ipmi_msghandler zram ip_tables
ccp ast bnxt_en drm_vram_helper drm_ttm_helper pkcs8_key_parser
asn1_decoder public_key oid_registry fuse ipv6 [last unloaded: 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]
[75721.624255] Code: 83 c0 01 38 d0 7c 0c 84 d2 74 08 4c 89 ff e8 57 59 64
e0 41 0f b7 74 24 62 ba e4 ff ff ff 48 c7 c7 a0 dc 33 a1 e8 c4 58 50 e2
<0f> 0b e9 9c fe ff ff 4d 8d a5 a0 02 00 00 4c 89 e7 e8 aa fb 5f e2
[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 btrfs vs zoned btrfs.
Set fs_info->max_extent_size to BTRFS_MAX_EXTENT_SIZE by default. On zoned
btrfs, 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")
Signed-off-by: Naohiro Aota <naohiro.aota@xxxxxxx>
---
fs/btrfs/ctree.h | 3 +++
fs/btrfs/disk-io.c | 2 ++
fs/btrfs/extent_io.c | 8 +++++++-
fs/btrfs/inode.c | 6 ++++--
fs/btrfs/zoned.c | 2 ++
5 files changed, 18 insertions(+), 3 deletions(-)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index e4879912c475..fca253bdb4b8 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1056,6 +1056,9 @@ struct btrfs_fs_info {
u32 csums_per_leaf;
u32 stripesize;
+ /* Maximum size of an extent. BTRFS_MAX_EXTENT_SIZE on regular btrfs. */
+ 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 76835394a61b..914557d59472 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3142,6 +3142,8 @@ 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 3194eca41635..cedc94a7d5b2 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2021,10 +2021,16 @@ 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;
+#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
+ /* The sanity tests may not set a valid fs_info. */
+ u64 max_bytes = fs_info ? fs_info->max_extent_size : BTRFS_MAX_EXTENT_SIZE;
+#else
+ u64 max_bytes = fs_info->max_extent_size;
+#endif
u64 delalloc_start;
u64 delalloc_end;
bool found;
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index b9485e19b696..155282dacc6e 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2201,6 +2201,7 @@ 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 */
@@ -2208,7 +2209,7 @@ 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;
@@ -2237,6 +2238,7 @@ 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;
@@ -2250,7 +2252,7 @@ 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 bdc533fa80ae..3b45b35aa945 100644
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -741,6 +741,8 @@ 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->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
