--- /dev/null
+From bfae3577aadad7c18806ee2a27d7620f898d6cfe Mon Sep 17 00:00:00 2001
+From: Sasha Levin <sashal@kernel.org>
+Date: Wed, 2 Dec 2020 11:55:58 +0000
+Subject: btrfs: fix deadlock when cloning inline extent and low on free
+ metadata space
+
+From: Filipe Manana <fdmanana@suse.com>
+
+[ Upstream commit 3d45f221ce627d13e2e6ef3274f06750c84a6542 ]
+
+When cloning an inline extent there are cases where we can not just copy
+the inline extent from the source range to the target range (e.g. when the
+target range starts at an offset greater than zero). In such cases we copy
+the inline extent's data into a page of the destination inode and then
+dirty that page. However, after that we will need to start a transaction
+for each processed extent and, if we are ever low on available metadata
+space, we may need to flush existing delalloc for all dirty inodes in an
+attempt to release metadata space - if that happens we may deadlock:
+
+* the async reclaim task queued a delalloc work to flush delalloc for
+ the destination inode of the clone operation;
+
+* the task executing that delalloc work gets blocked waiting for the
+ range with the dirty page to be unlocked, which is currently locked
+ by the task doing the clone operation;
+
+* the async reclaim task blocks waiting for the delalloc work to complete;
+
+* the cloning task is waiting on the waitqueue of its reservation ticket
+ while holding the range with the dirty page locked in the inode's
+ io_tree;
+
+* if metadata space is not released by some other task (like delalloc for
+ some other inode completing for example), the clone task waits forever
+ and as a consequence the delalloc work and async reclaim tasks will hang
+ forever as well. Releasing more space on the other hand may require
+ starting a transaction, which will hang as well when trying to reserve
+ metadata space, resulting in a deadlock between all these tasks.
+
+When this happens, traces like the following show up in dmesg/syslog:
+
+ [87452.323003] INFO: task kworker/u16:11:1810830 blocked for more than 120 seconds.
+ [87452.323644] Tainted: G B W 5.10.0-rc4-btrfs-next-73 #1
+ [87452.324248] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
+ [87452.324852] task:kworker/u16:11 state:D stack: 0 pid:1810830 ppid: 2 flags:0x00004000
+ [87452.325520] Workqueue: btrfs-flush_delalloc btrfs_work_helper [btrfs]
+ [87452.326136] Call Trace:
+ [87452.326737] __schedule+0x5d1/0xcf0
+ [87452.327390] schedule+0x45/0xe0
+ [87452.328174] lock_extent_bits+0x1e6/0x2d0 [btrfs]
+ [87452.328894] ? finish_wait+0x90/0x90
+ [87452.329474] btrfs_invalidatepage+0x32c/0x390 [btrfs]
+ [87452.330133] ? __mod_memcg_state+0x8e/0x160
+ [87452.330738] __extent_writepage+0x2d4/0x400 [btrfs]
+ [87452.331405] extent_write_cache_pages+0x2b2/0x500 [btrfs]
+ [87452.332007] ? lock_release+0x20e/0x4c0
+ [87452.332557] ? trace_hardirqs_on+0x1b/0xf0
+ [87452.333127] extent_writepages+0x43/0x90 [btrfs]
+ [87452.333653] ? lock_acquire+0x1a3/0x490
+ [87452.334177] do_writepages+0x43/0xe0
+ [87452.334699] ? __filemap_fdatawrite_range+0xa4/0x100
+ [87452.335720] __filemap_fdatawrite_range+0xc5/0x100
+ [87452.336500] btrfs_run_delalloc_work+0x17/0x40 [btrfs]
+ [87452.337216] btrfs_work_helper+0xf1/0x600 [btrfs]
+ [87452.337838] process_one_work+0x24e/0x5e0
+ [87452.338437] worker_thread+0x50/0x3b0
+ [87452.339137] ? process_one_work+0x5e0/0x5e0
+ [87452.339884] kthread+0x153/0x170
+ [87452.340507] ? kthread_mod_delayed_work+0xc0/0xc0
+ [87452.341153] ret_from_fork+0x22/0x30
+ [87452.341806] INFO: task kworker/u16:1:2426217 blocked for more than 120 seconds.
+ [87452.342487] Tainted: G B W 5.10.0-rc4-btrfs-next-73 #1
+ [87452.343274] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
+ [87452.344049] task:kworker/u16:1 state:D stack: 0 pid:2426217 ppid: 2 flags:0x00004000
+ [87452.344974] Workqueue: events_unbound btrfs_async_reclaim_metadata_space [btrfs]
+ [87452.345655] Call Trace:
+ [87452.346305] __schedule+0x5d1/0xcf0
+ [87452.346947] ? kvm_clock_read+0x14/0x30
+ [87452.347676] ? wait_for_completion+0x81/0x110
+ [87452.348389] schedule+0x45/0xe0
+ [87452.349077] schedule_timeout+0x30c/0x580
+ [87452.349718] ? _raw_spin_unlock_irqrestore+0x3c/0x60
+ [87452.350340] ? lock_acquire+0x1a3/0x490
+ [87452.351006] ? try_to_wake_up+0x7a/0xa20
+ [87452.351541] ? lock_release+0x20e/0x4c0
+ [87452.352040] ? lock_acquired+0x199/0x490
+ [87452.352517] ? wait_for_completion+0x81/0x110
+ [87452.353000] wait_for_completion+0xab/0x110
+ [87452.353490] start_delalloc_inodes+0x2af/0x390 [btrfs]
+ [87452.353973] btrfs_start_delalloc_roots+0x12d/0x250 [btrfs]
+ [87452.354455] flush_space+0x24f/0x660 [btrfs]
+ [87452.355063] btrfs_async_reclaim_metadata_space+0x1bb/0x480 [btrfs]
+ [87452.355565] process_one_work+0x24e/0x5e0
+ [87452.356024] worker_thread+0x20f/0x3b0
+ [87452.356487] ? process_one_work+0x5e0/0x5e0
+ [87452.356973] kthread+0x153/0x170
+ [87452.357434] ? kthread_mod_delayed_work+0xc0/0xc0
+ [87452.357880] ret_from_fork+0x22/0x30
+ (...)
+ < stack traces of several tasks waiting for the locks of the inodes of the
+ clone operation >
+ (...)
+ [92867.444138] RSP: 002b:00007ffc3371bbe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
+ [92867.444624] RAX: ffffffffffffffda RBX: 00007ffc3371bea0 RCX: 00007f61efe73f97
+ [92867.445116] RDX: 0000000000000000 RSI: 0000560fbd5d7a40 RDI: 0000560fbd5d8960
+ [92867.445595] RBP: 00007ffc3371beb0 R08: 0000000000000001 R09: 0000000000000003
+ [92867.446070] R10: 00007ffc3371b996 R11: 0000000000000246 R12: 0000000000000000
+ [92867.446820] R13: 000000000000001f R14: 00007ffc3371bea0 R15: 00007ffc3371beb0
+ [92867.447361] task:fsstress state:D stack: 0 pid:2508238 ppid:2508153 flags:0x00004000
+ [92867.447920] Call Trace:
+ [92867.448435] __schedule+0x5d1/0xcf0
+ [92867.448934] ? _raw_spin_unlock_irqrestore+0x3c/0x60
+ [92867.449423] schedule+0x45/0xe0
+ [92867.449916] __reserve_bytes+0x4a4/0xb10 [btrfs]
+ [92867.450576] ? finish_wait+0x90/0x90
+ [92867.451202] btrfs_reserve_metadata_bytes+0x29/0x190 [btrfs]
+ [92867.451815] btrfs_block_rsv_add+0x1f/0x50 [btrfs]
+ [92867.452412] start_transaction+0x2d1/0x760 [btrfs]
+ [92867.453216] clone_copy_inline_extent+0x333/0x490 [btrfs]
+ [92867.453848] ? lock_release+0x20e/0x4c0
+ [92867.454539] ? btrfs_search_slot+0x9a7/0xc30 [btrfs]
+ [92867.455218] btrfs_clone+0x569/0x7e0 [btrfs]
+ [92867.455952] btrfs_clone_files+0xf6/0x150 [btrfs]
+ [92867.456588] btrfs_remap_file_range+0x324/0x3d0 [btrfs]
+ [92867.457213] do_clone_file_range+0xd4/0x1f0
+ [92867.457828] vfs_clone_file_range+0x4d/0x230
+ [92867.458355] ? lock_release+0x20e/0x4c0
+ [92867.458890] ioctl_file_clone+0x8f/0xc0
+ [92867.459377] do_vfs_ioctl+0x342/0x750
+ [92867.459913] __x64_sys_ioctl+0x62/0xb0
+ [92867.460377] do_syscall_64+0x33/0x80
+ [92867.460842] entry_SYSCALL_64_after_hwframe+0x44/0xa9
+ (...)
+ < stack traces of more tasks blocked on metadata reservation like the clone
+ task above, because the async reclaim task has deadlocked >
+ (...)
+
+Another thing to notice is that the worker task that is deadlocked when
+trying to flush the destination inode of the clone operation is at
+btrfs_invalidatepage(). This is simply because the clone operation has a
+destination offset greater than the i_size and we only update the i_size
+of the destination file after cloning an extent (just like we do in the
+buffered write path).
+
+Since the async reclaim path uses btrfs_start_delalloc_roots() to trigger
+the flushing of delalloc for all inodes that have delalloc, add a runtime
+flag to an inode to signal it should not be flushed, and for inodes with
+that flag set, start_delalloc_inodes() will simply skip them. When the
+cloning code needs to dirty a page to copy an inline extent, set that flag
+on the inode and then clear it when the clone operation finishes.
+
+This could be sporadically triggered with test case generic/269 from
+fstests, which exercises many fsstress processes running in parallel with
+several dd processes filling up the entire filesystem.
+
+CC: stable@vger.kernel.org # 5.9+
+Fixes: 05a5a7621ce6 ("Btrfs: implement full reflink support for inline extents")
+Reviewed-by: Josef Bacik <josef@toxicpanda.com>
+Signed-off-by: Filipe Manana <fdmanana@suse.com>
+Reviewed-by: David Sterba <dsterba@suse.com>
+Signed-off-by: David Sterba <dsterba@suse.com>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ fs/btrfs/btrfs_inode.h | 9 +++++++++
+ fs/btrfs/ctree.h | 3 ++-
+ fs/btrfs/dev-replace.c | 2 +-
+ fs/btrfs/inode.c | 15 +++++++++++----
+ fs/btrfs/ioctl.c | 2 +-
+ fs/btrfs/reflink.c | 15 +++++++++++++++
+ fs/btrfs/space-info.c | 2 +-
+ 7 files changed, 40 insertions(+), 8 deletions(-)
+
+diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
+index c974f7fe614ac..8de4bf8edb9c0 100644
+--- a/fs/btrfs/btrfs_inode.h
++++ b/fs/btrfs/btrfs_inode.h
+@@ -42,6 +42,15 @@ enum {
+ * to an inode.
+ */
+ BTRFS_INODE_NO_XATTRS,
++ /*
++ * Set when we are in a context where we need to start a transaction and
++ * have dirty pages with the respective file range locked. This is to
++ * ensure that when reserving space for the transaction, if we are low
++ * on available space and need to flush delalloc, we will not flush
++ * delalloc for this inode, because that could result in a deadlock (on
++ * the file range, inode's io_tree).
++ */
++ BTRFS_INODE_NO_DELALLOC_FLUSH,
+ };
+
+ /* in memory btrfs inode */
+diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
+index 62461239600fc..e01545538e07f 100644
+--- a/fs/btrfs/ctree.h
++++ b/fs/btrfs/ctree.h
+@@ -3001,7 +3001,8 @@ int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
+ u32 min_type);
+
+ int btrfs_start_delalloc_snapshot(struct btrfs_root *root);
+-int btrfs_start_delalloc_roots(struct btrfs_fs_info *fs_info, u64 nr);
++int btrfs_start_delalloc_roots(struct btrfs_fs_info *fs_info, u64 nr,
++ bool in_reclaim_context);
+ int btrfs_set_extent_delalloc(struct btrfs_inode *inode, u64 start, u64 end,
+ unsigned int extra_bits,
+ struct extent_state **cached_state);
+diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
+index 10638537b9ef3..d297804631829 100644
+--- a/fs/btrfs/dev-replace.c
++++ b/fs/btrfs/dev-replace.c
+@@ -703,7 +703,7 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
+ * flush all outstanding I/O and inode extent mappings before the
+ * copy operation is declared as being finished
+ */
+- ret = btrfs_start_delalloc_roots(fs_info, U64_MAX);
++ ret = btrfs_start_delalloc_roots(fs_info, U64_MAX, false);
+ if (ret) {
+ mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
+ return ret;
+diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
+index 7e8d8169779d2..07479250221da 100644
+--- a/fs/btrfs/inode.c
++++ b/fs/btrfs/inode.c
+@@ -9389,7 +9389,8 @@ static struct btrfs_delalloc_work *btrfs_alloc_delalloc_work(struct inode *inode
+ * some fairly slow code that needs optimization. This walks the list
+ * of all the inodes with pending delalloc and forces them to disk.
+ */
+-static int start_delalloc_inodes(struct btrfs_root *root, u64 *nr, bool snapshot)
++static int start_delalloc_inodes(struct btrfs_root *root, u64 *nr, bool snapshot,
++ bool in_reclaim_context)
+ {
+ struct btrfs_inode *binode;
+ struct inode *inode;
+@@ -9410,6 +9411,11 @@ static int start_delalloc_inodes(struct btrfs_root *root, u64 *nr, bool snapshot
+
+ list_move_tail(&binode->delalloc_inodes,
+ &root->delalloc_inodes);
++
++ if (in_reclaim_context &&
++ test_bit(BTRFS_INODE_NO_DELALLOC_FLUSH, &binode->runtime_flags))
++ continue;
++
+ inode = igrab(&binode->vfs_inode);
+ if (!inode) {
+ cond_resched_lock(&root->delalloc_lock);
+@@ -9463,10 +9469,11 @@ int btrfs_start_delalloc_snapshot(struct btrfs_root *root)
+ if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state))
+ return -EROFS;
+
+- return start_delalloc_inodes(root, &nr, true);
++ return start_delalloc_inodes(root, &nr, true, false);
+ }
+
+-int btrfs_start_delalloc_roots(struct btrfs_fs_info *fs_info, u64 nr)
++int btrfs_start_delalloc_roots(struct btrfs_fs_info *fs_info, u64 nr,
++ bool in_reclaim_context)
+ {
+ struct btrfs_root *root;
+ struct list_head splice;
+@@ -9489,7 +9496,7 @@ int btrfs_start_delalloc_roots(struct btrfs_fs_info *fs_info, u64 nr)
+ &fs_info->delalloc_roots);
+ spin_unlock(&fs_info->delalloc_root_lock);
+
+- ret = start_delalloc_inodes(root, &nr, false);
++ ret = start_delalloc_inodes(root, &nr, false, in_reclaim_context);
+ btrfs_put_root(root);
+ if (ret < 0)
+ goto out;
+diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
+index e8ca229a216be..bd46e107f955e 100644
+--- a/fs/btrfs/ioctl.c
++++ b/fs/btrfs/ioctl.c
+@@ -4940,7 +4940,7 @@ long btrfs_ioctl(struct file *file, unsigned int
+ case BTRFS_IOC_SYNC: {
+ int ret;
+
+- ret = btrfs_start_delalloc_roots(fs_info, U64_MAX);
++ ret = btrfs_start_delalloc_roots(fs_info, U64_MAX, false);
+ if (ret)
+ return ret;
+ ret = btrfs_sync_fs(inode->i_sb, 1);
+diff --git a/fs/btrfs/reflink.c b/fs/btrfs/reflink.c
+index 99aa87c089121..a646af95dd100 100644
+--- a/fs/btrfs/reflink.c
++++ b/fs/btrfs/reflink.c
+@@ -89,6 +89,19 @@ static int copy_inline_to_page(struct btrfs_inode *inode,
+ if (ret)
+ goto out_unlock;
+
++ /*
++ * After dirtying the page our caller will need to start a transaction,
++ * and if we are low on metadata free space, that can cause flushing of
++ * delalloc for all inodes in order to get metadata space released.
++ * However we are holding the range locked for the whole duration of
++ * the clone/dedupe operation, so we may deadlock if that happens and no
++ * other task releases enough space. So mark this inode as not being
++ * possible to flush to avoid such deadlock. We will clear that flag
++ * when we finish cloning all extents, since a transaction is started
++ * after finding each extent to clone.
++ */
++ set_bit(BTRFS_INODE_NO_DELALLOC_FLUSH, &inode->runtime_flags);
++
+ if (comp_type == BTRFS_COMPRESS_NONE) {
+ char *map;
+
+@@ -547,6 +560,8 @@ static int btrfs_clone(struct inode *src, struct inode *inode,
+ out:
+ btrfs_free_path(path);
+ kvfree(buf);
++ clear_bit(BTRFS_INODE_NO_DELALLOC_FLUSH, &BTRFS_I(inode)->runtime_flags);
++
+ return ret;
+ }
+
+diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
+index 64099565ab8f5..67e55c5479b8e 100644
+--- a/fs/btrfs/space-info.c
++++ b/fs/btrfs/space-info.c
+@@ -532,7 +532,7 @@ static void shrink_delalloc(struct btrfs_fs_info *fs_info,
+
+ loops = 0;
+ while ((delalloc_bytes || dio_bytes) && loops < 3) {
+- btrfs_start_delalloc_roots(fs_info, items);
++ btrfs_start_delalloc_roots(fs_info, items, true);
+
+ loops++;
+ if (wait_ordered && !trans) {
+--
+2.27.0
+
--- /dev/null
+From 5301408ee15e0cd9454c3f57356c055c98158a0e Mon Sep 17 00:00:00 2001
+From: Sasha Levin <sashal@kernel.org>
+Date: Thu, 7 Jan 2021 17:08:30 -0500
+Subject: btrfs: shrink delalloc pages instead of full inodes
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+From: Josef Bacik <josef@toxicpanda.com>
+
+[ Upstream commit e076ab2a2ca70a0270232067cd49f76cd92efe64 ]
+
+Commit 38d715f494f2 ("btrfs: use btrfs_start_delalloc_roots in
+shrink_delalloc") cleaned up how we do delalloc shrinking by utilizing
+some infrastructure we have in place to flush inodes that we use for
+device replace and snapshot. However this introduced a pretty serious
+performance regression. To reproduce the user untarred the source
+tarball of Firefox (360MiB xz compressed/1.5GiB uncompressed), and would
+see it take anywhere from 5 to 20 times as long to untar in 5.10
+compared to 5.9. This was observed on fast devices (SSD and better) and
+not on HDD.
+
+The root cause is because before we would generally use the normal
+writeback path to reclaim delalloc space, and for this we would provide
+it with the number of pages we wanted to flush. The referenced commit
+changed this to flush that many inodes, which drastically increased the
+amount of space we were flushing in certain cases, which severely
+affected performance.
+
+We cannot revert this patch unfortunately because of 3d45f221ce62
+("btrfs: fix deadlock when cloning inline extent and low on free
+metadata space") which requires the ability to skip flushing inodes that
+are being cloned in certain scenarios, which means we need to keep using
+our flushing infrastructure or risk re-introducing the deadlock.
+
+Instead to fix this problem we can go back to providing
+btrfs_start_delalloc_roots with a number of pages to flush, and then set
+up a writeback_control and utilize sync_inode() to handle the flushing
+for us. This gives us the same behavior we had prior to the fix, while
+still allowing us to avoid the deadlock that was fixed by Filipe. I
+redid the users original test and got the following results on one of
+our test machines (256GiB of ram, 56 cores, 2TiB Intel NVMe drive)
+
+ 5.9 0m54.258s
+ 5.10 1m26.212s
+ 5.10+patch 0m38.800s
+
+5.10+patch is significantly faster than plain 5.9 because of my patch
+series "Change data reservations to use the ticketing infra" which
+contained the patch that introduced the regression, but generally
+improved the overall ENOSPC flushing mechanisms.
+
+Additional testing on consumer-grade SSD (8GiB ram, 8 CPU) confirm
+the results:
+
+ 5.10.5 4m00s
+ 5.10.5+patch 1m08s
+ 5.11-rc2 5m14s
+ 5.11-rc2+patch 1m30s
+
+Reported-by: René Rebe <rene@exactcode.de>
+Fixes: 38d715f494f2 ("btrfs: use btrfs_start_delalloc_roots in shrink_delalloc")
+CC: stable@vger.kernel.org # 5.10
+Signed-off-by: Josef Bacik <josef@toxicpanda.com>
+Tested-by: David Sterba <dsterba@suse.com>
+Reviewed-by: David Sterba <dsterba@suse.com>
+[ add my test results ]
+Signed-off-by: David Sterba <dsterba@suse.com>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ fs/btrfs/inode.c | 60 +++++++++++++++++++++++++++++++------------
+ fs/btrfs/space-info.c | 4 ++-
+ 2 files changed, 46 insertions(+), 18 deletions(-)
+
+diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
+index 07479250221da..acc47e2ffb46b 100644
+--- a/fs/btrfs/inode.c
++++ b/fs/btrfs/inode.c
+@@ -9389,7 +9389,8 @@ static struct btrfs_delalloc_work *btrfs_alloc_delalloc_work(struct inode *inode
+ * some fairly slow code that needs optimization. This walks the list
+ * of all the inodes with pending delalloc and forces them to disk.
+ */
+-static int start_delalloc_inodes(struct btrfs_root *root, u64 *nr, bool snapshot,
++static int start_delalloc_inodes(struct btrfs_root *root,
++ struct writeback_control *wbc, bool snapshot,
+ bool in_reclaim_context)
+ {
+ struct btrfs_inode *binode;
+@@ -9398,6 +9399,7 @@ static int start_delalloc_inodes(struct btrfs_root *root, u64 *nr, bool snapshot
+ struct list_head works;
+ struct list_head splice;
+ int ret = 0;
++ bool full_flush = wbc->nr_to_write == LONG_MAX;
+
+ INIT_LIST_HEAD(&works);
+ INIT_LIST_HEAD(&splice);
+@@ -9426,18 +9428,24 @@ static int start_delalloc_inodes(struct btrfs_root *root, u64 *nr, bool snapshot
+ if (snapshot)
+ set_bit(BTRFS_INODE_SNAPSHOT_FLUSH,
+ &binode->runtime_flags);
+- work = btrfs_alloc_delalloc_work(inode);
+- if (!work) {
+- iput(inode);
+- ret = -ENOMEM;
+- goto out;
+- }
+- list_add_tail(&work->list, &works);
+- btrfs_queue_work(root->fs_info->flush_workers,
+- &work->work);
+- if (*nr != U64_MAX) {
+- (*nr)--;
+- if (*nr == 0)
++ if (full_flush) {
++ work = btrfs_alloc_delalloc_work(inode);
++ if (!work) {
++ iput(inode);
++ ret = -ENOMEM;
++ goto out;
++ }
++ list_add_tail(&work->list, &works);
++ btrfs_queue_work(root->fs_info->flush_workers,
++ &work->work);
++ } else {
++ ret = sync_inode(inode, wbc);
++ if (!ret &&
++ test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
++ &BTRFS_I(inode)->runtime_flags))
++ ret = sync_inode(inode, wbc);
++ btrfs_add_delayed_iput(inode);
++ if (ret || wbc->nr_to_write <= 0)
+ goto out;
+ }
+ cond_resched();
+@@ -9463,18 +9471,29 @@ static int start_delalloc_inodes(struct btrfs_root *root, u64 *nr, bool snapshot
+
+ int btrfs_start_delalloc_snapshot(struct btrfs_root *root)
+ {
++ struct writeback_control wbc = {
++ .nr_to_write = LONG_MAX,
++ .sync_mode = WB_SYNC_NONE,
++ .range_start = 0,
++ .range_end = LLONG_MAX,
++ };
+ struct btrfs_fs_info *fs_info = root->fs_info;
+- u64 nr = U64_MAX;
+
+ if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state))
+ return -EROFS;
+
+- return start_delalloc_inodes(root, &nr, true, false);
++ return start_delalloc_inodes(root, &wbc, true, false);
+ }
+
+ int btrfs_start_delalloc_roots(struct btrfs_fs_info *fs_info, u64 nr,
+ bool in_reclaim_context)
+ {
++ struct writeback_control wbc = {
++ .nr_to_write = (nr == U64_MAX) ? LONG_MAX : (unsigned long)nr,
++ .sync_mode = WB_SYNC_NONE,
++ .range_start = 0,
++ .range_end = LLONG_MAX,
++ };
+ struct btrfs_root *root;
+ struct list_head splice;
+ int ret;
+@@ -9488,6 +9507,13 @@ int btrfs_start_delalloc_roots(struct btrfs_fs_info *fs_info, u64 nr,
+ spin_lock(&fs_info->delalloc_root_lock);
+ list_splice_init(&fs_info->delalloc_roots, &splice);
+ while (!list_empty(&splice) && nr) {
++ /*
++ * Reset nr_to_write here so we know that we're doing a full
++ * flush.
++ */
++ if (nr == U64_MAX)
++ wbc.nr_to_write = LONG_MAX;
++
+ root = list_first_entry(&splice, struct btrfs_root,
+ delalloc_root);
+ root = btrfs_grab_root(root);
+@@ -9496,9 +9522,9 @@ int btrfs_start_delalloc_roots(struct btrfs_fs_info *fs_info, u64 nr,
+ &fs_info->delalloc_roots);
+ spin_unlock(&fs_info->delalloc_root_lock);
+
+- ret = start_delalloc_inodes(root, &nr, false, in_reclaim_context);
++ ret = start_delalloc_inodes(root, &wbc, false, in_reclaim_context);
+ btrfs_put_root(root);
+- if (ret < 0)
++ if (ret < 0 || wbc.nr_to_write <= 0)
+ goto out;
+ spin_lock(&fs_info->delalloc_root_lock);
+ }
+diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
+index 67e55c5479b8e..e8347461c8ddd 100644
+--- a/fs/btrfs/space-info.c
++++ b/fs/btrfs/space-info.c
+@@ -532,7 +532,9 @@ static void shrink_delalloc(struct btrfs_fs_info *fs_info,
+
+ loops = 0;
+ while ((delalloc_bytes || dio_bytes) && loops < 3) {
+- btrfs_start_delalloc_roots(fs_info, items, true);
++ u64 nr_pages = min(delalloc_bytes, to_reclaim) >> PAGE_SHIFT;
++
++ btrfs_start_delalloc_roots(fs_info, nr_pages, true);
+
+ loops++;
+ if (wait_ordered && !trans) {
+--
+2.27.0
+
--- /dev/null
+From 6eb244d3bc63d0f0918bb81bbe3b4baec0ca6a7e Mon Sep 17 00:00:00 2001
+From: Sasha Levin <sashal@kernel.org>
+Date: Fri, 13 Nov 2020 11:21:49 +0000
+Subject: btrfs: skip unnecessary searches for xattrs when logging an inode
+
+From: Filipe Manana <fdmanana@suse.com>
+
+[ Upstream commit f2f121ab500d0457cc9c6f54269d21ffdf5bd304 ]
+
+Every time we log an inode we lookup in the fs/subvol tree for xattrs and
+if we have any, log them into the log tree. However it is very common to
+have inodes without any xattrs, so doing the search wastes times, but more
+importantly it adds contention on the fs/subvol tree locks, either making
+the logging code block and wait for tree locks or making the logging code
+making other concurrent operations block and wait.
+
+The most typical use cases where xattrs are used are when capabilities or
+ACLs are defined for an inode, or when SELinux is enabled.
+
+This change makes the logging code detect when an inode does not have
+xattrs and skip the xattrs search the next time the inode is logged,
+unless the inode is evicted and loaded again or a xattr is added to the
+inode. Therefore skipping the search for xattrs on inodes that don't ever
+have xattrs and are fsynced with some frequency.
+
+The following script that calls dbench was used to measure the impact of
+this change on a VM with 8 CPUs, 16Gb of ram, using a raw NVMe device
+directly (no intermediary filesystem on the host) and using a non-debug
+kernel (default configuration on Debian distributions):
+
+ $ cat test.sh
+ #!/bin/bash
+
+ DEV=/dev/sdk
+ MNT=/mnt/sdk
+ MOUNT_OPTIONS="-o ssd"
+
+ mkfs.btrfs -f -m single -d single $DEV
+ mount $MOUNT_OPTIONS $DEV $MNT
+
+ dbench -D $MNT -t 200 40
+
+ umount $MNT
+
+The results before this change:
+
+ Operation Count AvgLat MaxLat
+ ----------------------------------------
+ NTCreateX 5761605 0.172 312.057
+ Close 4232452 0.002 10.927
+ Rename 243937 1.406 277.344
+ Unlink 1163456 0.631 298.402
+ Deltree 160 11.581 221.107
+ Mkdir 80 0.003 0.005
+ Qpathinfo 5221410 0.065 122.309
+ Qfileinfo 915432 0.001 3.333
+ Qfsinfo 957555 0.003 3.992
+ Sfileinfo 469244 0.023 20.494
+ Find 2018865 0.448 123.659
+ WriteX 2874851 0.049 118.529
+ ReadX 9030579 0.004 21.654
+ LockX 18754 0.003 4.423
+ UnlockX 18754 0.002 0.331
+ Flush 403792 10.944 359.494
+
+Throughput 908.444 MB/sec 40 clients 40 procs max_latency=359.500 ms
+
+The results after this change:
+
+ Operation Count AvgLat MaxLat
+ ----------------------------------------
+ NTCreateX 6442521 0.159 230.693
+ Close 4732357 0.002 10.972
+ Rename 272809 1.293 227.398
+ Unlink 1301059 0.563 218.500
+ Deltree 160 7.796 54.887
+ Mkdir 80 0.008 0.478
+ Qpathinfo 5839452 0.047 124.330
+ Qfileinfo 1023199 0.001 4.996
+ Qfsinfo 1070760 0.003 5.709
+ Sfileinfo 524790 0.033 21.765
+ Find 2257658 0.314 125.611
+ WriteX 3211520 0.040 232.135
+ ReadX 10098969 0.004 25.340
+ LockX 20974 0.003 1.569
+ UnlockX 20974 0.002 3.475
+ Flush 451553 10.287 331.037
+
+Throughput 1011.77 MB/sec 40 clients 40 procs max_latency=331.045 ms
+
++10.8% throughput, -8.2% max latency
+
+Reviewed-by: Josef Bacik <josef@toxicpanda.com>
+Signed-off-by: Filipe Manana <fdmanana@suse.com>
+Reviewed-by: David Sterba <dsterba@suse.com>
+Signed-off-by: David Sterba <dsterba@suse.com>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ fs/btrfs/btrfs_inode.h | 7 +++++++
+ fs/btrfs/tree-log.c | 8 ++++++++
+ fs/btrfs/xattr.c | 4 +++-
+ 3 files changed, 18 insertions(+), 1 deletion(-)
+
+diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
+index 92dd86bceae31..c974f7fe614ac 100644
+--- a/fs/btrfs/btrfs_inode.h
++++ b/fs/btrfs/btrfs_inode.h
+@@ -35,6 +35,13 @@ enum {
+ BTRFS_INODE_IN_DELALLOC_LIST,
+ BTRFS_INODE_HAS_PROPS,
+ BTRFS_INODE_SNAPSHOT_FLUSH,
++ /*
++ * Set and used when logging an inode and it serves to signal that an
++ * inode does not have xattrs, so subsequent fsyncs can avoid searching
++ * for xattrs to log. This bit must be cleared whenever a xattr is added
++ * to an inode.
++ */
++ BTRFS_INODE_NO_XATTRS,
+ };
+
+ /* in memory btrfs inode */
+diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
+index 56cbc1706b6f7..5b11bb9770664 100644
+--- a/fs/btrfs/tree-log.c
++++ b/fs/btrfs/tree-log.c
+@@ -4571,6 +4571,10 @@ static int btrfs_log_all_xattrs(struct btrfs_trans_handle *trans,
+ const u64 ino = btrfs_ino(inode);
+ int ins_nr = 0;
+ int start_slot = 0;
++ bool found_xattrs = false;
++
++ if (test_bit(BTRFS_INODE_NO_XATTRS, &inode->runtime_flags))
++ return 0;
+
+ key.objectid = ino;
+ key.type = BTRFS_XATTR_ITEM_KEY;
+@@ -4609,6 +4613,7 @@ static int btrfs_log_all_xattrs(struct btrfs_trans_handle *trans,
+ start_slot = slot;
+ ins_nr++;
+ path->slots[0]++;
++ found_xattrs = true;
+ cond_resched();
+ }
+ if (ins_nr > 0) {
+@@ -4618,6 +4623,9 @@ static int btrfs_log_all_xattrs(struct btrfs_trans_handle *trans,
+ return ret;
+ }
+
++ if (!found_xattrs)
++ set_bit(BTRFS_INODE_NO_XATTRS, &inode->runtime_flags);
++
+ return 0;
+ }
+
+diff --git a/fs/btrfs/xattr.c b/fs/btrfs/xattr.c
+index 95d9aebff2c4b..e51774201d53b 100644
+--- a/fs/btrfs/xattr.c
++++ b/fs/btrfs/xattr.c
+@@ -213,9 +213,11 @@ int btrfs_setxattr(struct btrfs_trans_handle *trans, struct inode *inode,
+ }
+ out:
+ btrfs_free_path(path);
+- if (!ret)
++ if (!ret) {
+ set_bit(BTRFS_INODE_COPY_EVERYTHING,
+ &BTRFS_I(inode)->runtime_flags);
++ clear_bit(BTRFS_INODE_NO_XATTRS, &BTRFS_I(inode)->runtime_flags);
++ }
+ return ret;
+ }
+
+--
+2.27.0
+
projects / thirdparty / kernel / stable-queue.git / commitdiff
