[PATCH v3 0/5] btrfs: fix relocation on RAID stripe-tree filesystems

[PATCH v3 0/5] btrfs: fix relocation on RAID stripe-tree filesystems

[Johannes Thumshirn]

When doing relocation on RST backed filesystems, there is a possibility of
a scatter-gather list corruption.

See patch 4 for details.

CI Link: https://github.com/btrfs/linux/actions/runs/10143804038

---
Changes in v3:
- Re-base onto for-next with folio->page conversion applied.
- Collected reviews.
- Link to v2: https://lore.kernel.org/r/20240730-debug-v2-0-38e6607ecba6@kernel.org

Changes in v2:
- Change RST lookup error message to debug
- Link to v1: https://lore.kernel.org/r/20240729-debug-v1-0-f0b3d78d9438@kernel.org

---
Johannes Thumshirn (5):
      btrfs: don't dump stripe-tree on lookup error
      btrfs: rename btrfs_io_stripe::is_scrub to rst_search_commit_root
      btrfs: set rst_search_commit_root in case of relocation
      btrfs: don't readahead the relocation inode on RST
      btrfs: change RST lookup error message to debug

 fs/btrfs/bio.c              |  3 ++-
 fs/btrfs/raid-stripe-tree.c |  8 +++-----
 fs/btrfs/relocation.c       | 14 ++++++++++----
 fs/btrfs/scrub.c            |  2 +-
 fs/btrfs/volumes.h          |  2 +-
 5 files changed, 17 insertions(+), 12 deletions(-)
---
base-commit: 27d58e7d992b58ae7091270dc179e1dcbd6561f8
change-id: 20240726-debug-f1fe805ea37b

Best regards,
-- 
Johannes Thumshirn <jth@kernel.org>

[PATCH v3 1/5] btrfs: don't dump stripe-tree on lookup error

[Johannes Thumshirn]

From: Johannes Thumshirn <johannes.thumshirn@wdc.com>

This just creates unnecessary noise and doesn't provide any insights into
debugging RAID stripe-tree related issues.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 fs/btrfs/raid-stripe-tree.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/fs/btrfs/raid-stripe-tree.c b/fs/btrfs/raid-stripe-tree.c
index bd06ff795691..c1c74f310e8b 100644
--- a/fs/btrfs/raid-stripe-tree.c
+++ b/fs/btrfs/raid-stripe-tree.c
@@ -284,8 +284,6 @@ int btrfs_get_raid_extent_offset(struct btrfs_fs_info *fs_info,
 	if (ret > 0)
 		ret = -ENOENT;
 	if (ret && ret != -EIO && !stripe->is_scrub) {
-		if (IS_ENABLED(CONFIG_BTRFS_DEBUG))
-			btrfs_print_tree(leaf, 1);
 		btrfs_err(fs_info,
 		"cannot find raid-stripe for logical [%llu, %llu] devid %llu, profile %s",
 			  logical, logical + *length, stripe->dev->devid,

-- 
2.43.0

[PATCH v3 2/5] btrfs: rename btrfs_io_stripe::is_scrub to rst_search_commit_root

[Johannes Thumshirn]

From: Johannes Thumshirn <johannes.thumshirn@wdc.com>

Rename 'btrfs_io_stripe::is_scrub' to 'rst_search_commit_root'. While
'is_scrub' describes the state of the io_stripe (it is a stripe submitted
by scrub) it does not describe the purpose, namely looking at the commit
root when searching RAID stripe-tree entries.

Renaming the stripe to rst_search_commit_root describes this purpose.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 fs/btrfs/bio.c              | 2 +-
 fs/btrfs/raid-stripe-tree.c | 4 ++--
 fs/btrfs/scrub.c            | 2 +-
 fs/btrfs/volumes.h          | 2 +-
 4 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/fs/btrfs/bio.c b/fs/btrfs/bio.c
index f04d93109960..dfb32f7d3fc2 100644
--- a/fs/btrfs/bio.c
+++ b/fs/btrfs/bio.c
@@ -679,7 +679,7 @@ static bool btrfs_submit_chunk(struct btrfs_bio *bbio, int mirror_num)
 	blk_status_t ret;
 	int error;
 
-	smap.is_scrub = !bbio->inode;
+	smap.rst_search_commit_root = !bbio->inode;
 
 	btrfs_bio_counter_inc_blocked(fs_info);
 	error = btrfs_map_block(fs_info, btrfs_op(bio), logical, &map_length,
diff --git a/fs/btrfs/raid-stripe-tree.c b/fs/btrfs/raid-stripe-tree.c
index c1c74f310e8b..28a545367be7 100644
--- a/fs/btrfs/raid-stripe-tree.c
+++ b/fs/btrfs/raid-stripe-tree.c
@@ -210,7 +210,7 @@ int btrfs_get_raid_extent_offset(struct btrfs_fs_info *fs_info,
 	if (!path)
 		return -ENOMEM;
 
-	if (stripe->is_scrub) {
+	if (stripe->rst_search_commit_root) {
 		path->skip_locking = 1;
 		path->search_commit_root = 1;
 	}
@@ -283,7 +283,7 @@ int btrfs_get_raid_extent_offset(struct btrfs_fs_info *fs_info,
 out:
 	if (ret > 0)
 		ret = -ENOENT;
-	if (ret && ret != -EIO && !stripe->is_scrub) {
+	if (ret && ret != -EIO && !stripe->rst_search_commit_root) {
 		btrfs_err(fs_info,
 		"cannot find raid-stripe for logical [%llu, %llu] devid %llu, profile %s",
 			  logical, logical + *length, stripe->dev->devid,
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 0de9162ff481..b3afa6365823 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -1694,7 +1694,7 @@ static void scrub_submit_extent_sector_read(struct scrub_ctx *sctx,
 					    (i << fs_info->sectorsize_bits);
 			int err;
 
-			io_stripe.is_scrub = true;
+			io_stripe.rst_search_commit_root = true;
 			stripe_len = (nr_sectors - i) << fs_info->sectorsize_bits;
 			/*
 			 * For RST cases, we need to manually split the bbio to
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index c947187539dd..03d2d60afe0c 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -444,7 +444,7 @@ struct btrfs_io_stripe {
 	/* Block mapping. */
 	u64 physical;
 	u64 length;
-	bool is_scrub;
+	bool rst_search_commit_root;
 	/* For the endio handler. */
 	struct btrfs_io_context *bioc;
 };

-- 
2.43.0

[PATCH v3 3/5] btrfs: set rst_search_commit_root in case of relocation

[Johannes Thumshirn]

From: Johannes Thumshirn <johannes.thumshirn@wdc.com>

Set rst_search_commit_root in the btrfs_io_stripe we're passing to
btrfs_map_block() in case we're doing data relocation.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 fs/btrfs/bio.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/bio.c b/fs/btrfs/bio.c
index dfb32f7d3fc2..c6563616c813 100644
--- a/fs/btrfs/bio.c
+++ b/fs/btrfs/bio.c
@@ -679,7 +679,8 @@ static bool btrfs_submit_chunk(struct btrfs_bio *bbio, int mirror_num)
 	blk_status_t ret;
 	int error;
 
-	smap.rst_search_commit_root = !bbio->inode;
+	smap.rst_search_commit_root =
+		(!bbio->inode || btrfs_is_data_reloc_root(inode->root));
 
 	btrfs_bio_counter_inc_blocked(fs_info);
 	error = btrfs_map_block(fs_info, btrfs_op(bio), logical, &map_length,

-- 
2.43.0

[PATCH v3 4/5] btrfs: don't readahead the relocation inode on RST

[Johannes Thumshirn]

From: Johannes Thumshirn <jthumshirn@wdc.com>

On relocation we're doing readahead on the relocation inode, but if the
filesystem is backed by a RAID stripe tree we can get ENOENT (e.g. due to
preallocated extents not being mapped in the RST) from the lookup.

But readahead doesn't handle the error and submits invalid reads to the
device, causing an assertion in the scatter-gather list code:

  BTRFS info (device nvme1n1): balance: start -d -m -s
  BTRFS info (device nvme1n1): relocating block group 6480920576 flags data|raid0
  BTRFS error (device nvme1n1): cannot find raid-stripe for logical [6481928192, 6481969152] devid 2, profile raid0
  ------------[ cut here ]------------
  kernel BUG at include/linux/scatterlist.h:115!
  Oops: invalid opcode: 0000 [#1] PREEMPT SMP PTI
  CPU: 0 PID: 1012 Comm: btrfs Not tainted 6.10.0-rc7+ #567
  RIP: 0010:__blk_rq_map_sg+0x339/0x4a0
  RSP: 0018:ffffc90001a43820 EFLAGS: 00010202
  RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffea00045d4802
  RDX: 0000000117520000 RSI: 0000000000000000 RDI: ffff8881027d1000
  RBP: 0000000000003000 R08: ffffea00045d4902 R09: 0000000000000000
  R10: 0000000000000000 R11: 0000000000001000 R12: ffff8881003d10b8
  R13: ffffc90001a438f0 R14: 0000000000000000 R15: 0000000000003000
  FS:  00007fcc048a6900(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 000000002cd11000 CR3: 00000001109ea001 CR4: 0000000000370eb0
  Call Trace:
   <TASK>
   ? __die_body.cold+0x14/0x25
   ? die+0x2e/0x50
   ? do_trap+0xca/0x110
   ? do_error_trap+0x65/0x80
   ? __blk_rq_map_sg+0x339/0x4a0
   ? exc_invalid_op+0x50/0x70
   ? __blk_rq_map_sg+0x339/0x4a0
   ? asm_exc_invalid_op+0x1a/0x20
   ? __blk_rq_map_sg+0x339/0x4a0
   nvme_prep_rq.part.0+0x9d/0x770
   nvme_queue_rq+0x7d/0x1e0
   __blk_mq_issue_directly+0x2a/0x90
   ? blk_mq_get_budget_and_tag+0x61/0x90
   blk_mq_try_issue_list_directly+0x56/0xf0
   blk_mq_flush_plug_list.part.0+0x52b/0x5d0
   __blk_flush_plug+0xc6/0x110
   blk_finish_plug+0x28/0x40
   read_pages+0x160/0x1c0
   page_cache_ra_unbounded+0x109/0x180
   relocate_file_extent_cluster+0x611/0x6a0
   ? btrfs_search_slot+0xba4/0xd20
   ? balance_dirty_pages_ratelimited_flags+0x26/0xb00
   relocate_data_extent.constprop.0+0x134/0x160
   relocate_block_group+0x3f2/0x500
   btrfs_relocate_block_group+0x250/0x430
   btrfs_relocate_chunk+0x3f/0x130
   btrfs_balance+0x71b/0xef0
   ? kmalloc_trace_noprof+0x13b/0x280
   btrfs_ioctl+0x2c2e/0x3030
   ? kvfree_call_rcu+0x1e6/0x340
   ? list_lru_add_obj+0x66/0x80
   ? mntput_no_expire+0x3a/0x220
   __x64_sys_ioctl+0x96/0xc0
   do_syscall_64+0x54/0x110
   entry_SYSCALL_64_after_hwframe+0x76/0x7e
  RIP: 0033:0x7fcc04514f9b
  Code: Unable to access opcode bytes at 0x7fcc04514f71.
  RSP: 002b:00007ffeba923370 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
  RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fcc04514f9b
  RDX: 00007ffeba923460 RSI: 00000000c4009420 RDI: 0000000000000003
  RBP: 0000000000000000 R08: 0000000000000013 R09: 0000000000000001
  R10: 00007fcc043fbba8 R11: 0000000000000246 R12: 00007ffeba924fc5
  R13: 00007ffeba923460 R14: 0000000000000002 R15: 00000000004d4bb0
   </TASK>
  Modules linked in:
  ---[ end trace 0000000000000000 ]---
  RIP: 0010:__blk_rq_map_sg+0x339/0x4a0
  RSP: 0018:ffffc90001a43820 EFLAGS: 00010202
  RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffea00045d4802
  RDX: 0000000117520000 RSI: 0000000000000000 RDI: ffff8881027d1000
  RBP: 0000000000003000 R08: ffffea00045d4902 R09: 0000000000000000
  R10: 0000000000000000 R11: 0000000000001000 R12: ffff8881003d10b8
  R13: ffffc90001a438f0 R14: 0000000000000000 R15: 0000000000003000
  FS:  00007fcc048a6900(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007fcc04514f71 CR3: 00000001109ea001 CR4: 0000000000370eb0
  Kernel panic - not syncing: Fatal exception
  Kernel Offset: disabled
  ---[ end Kernel panic - not syncing: Fatal exception ]---

So in case of a relocation on a RAID stripe-tree based file system, skip
the readahead.

Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 fs/btrfs/relocation.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 0533d0f82dc9..72fb43b4d27c 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -36,6 +36,7 @@
 #include "relocation.h"
 #include "super.h"
 #include "tree-checker.h"
+#include "raid-stripe-tree.h"
 
 /*
  * Relocation overview
@@ -2965,21 +2966,26 @@ static int relocate_one_folio(struct reloc_control *rc,
 	u64 folio_end;
 	u64 cur;
 	int ret;
+	bool use_rst =
+		btrfs_need_stripe_tree_update(fs_info, rc->block_group->flags);
 
 	ASSERT(index <= last_index);
 	folio = filemap_lock_folio(inode->i_mapping, index);
 	if (IS_ERR(folio)) {
-		page_cache_sync_readahead(inode->i_mapping, ra, NULL,
-					  index, last_index + 1 - index);
+		if (!use_rst)
+			page_cache_sync_readahead(inode->i_mapping, ra, NULL,
+						  index,
+						  last_index + 1 - index);
 		folio = __filemap_get_folio(inode->i_mapping, index,
-					    FGP_LOCK | FGP_ACCESSED | FGP_CREAT, mask);
+					    FGP_LOCK | FGP_ACCESSED | FGP_CREAT,
+					    mask);
 		if (IS_ERR(folio))
 			return PTR_ERR(folio);
 	}
 
 	WARN_ON(folio_order(folio));
 
-	if (folio_test_readahead(folio))
+	if (folio_test_readahead(folio) && !use_rst)
 		page_cache_async_readahead(inode->i_mapping, ra, NULL,
 					   folio, last_index + 1 - index);
 

-- 
2.43.0

[PATCH v3 5/5] btrfs: change RST lookup error message to debug

[Johannes Thumshirn]

From: Johannes Thumshirn <johannes.thumshirn@wdc.com>

Now that RAID stripe-tree lookup failures are not treated as a fatal issue
any more, change the RAID stripe-tree lookup error message to debug level.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 fs/btrfs/raid-stripe-tree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/raid-stripe-tree.c b/fs/btrfs/raid-stripe-tree.c
index 28a545367be7..4c859b550f6c 100644
--- a/fs/btrfs/raid-stripe-tree.c
+++ b/fs/btrfs/raid-stripe-tree.c
@@ -284,7 +284,7 @@ int btrfs_get_raid_extent_offset(struct btrfs_fs_info *fs_info,
 	if (ret > 0)
 		ret = -ENOENT;
 	if (ret && ret != -EIO && !stripe->rst_search_commit_root) {
-		btrfs_err(fs_info,
+		btrfs_debug(fs_info,
 		"cannot find raid-stripe for logical [%llu, %llu] devid %llu, profile %s",
 			  logical, logical + *length, stripe->dev->devid,
 			  btrfs_bg_type_to_raid_name(map_type));

-- 
2.43.0

Re: [PATCH v3 3/5] btrfs: set rst_search_commit_root in case of relocation

[David Sterba]

On Wed, Jul 31, 2024 at 10:43:05PM +0200, Johannes Thumshirn wrote:
> From: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> 
> Set rst_search_commit_root in the btrfs_io_stripe we're passing to
> btrfs_map_block() in case we're doing data relocation.
> 
> Reviewed-by: Josef Bacik <josef@toxicpanda.com>
> Reviewed-by: Qu Wenruo <wqu@suse.com>
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> ---
>  fs/btrfs/bio.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/btrfs/bio.c b/fs/btrfs/bio.c
> index dfb32f7d3fc2..c6563616c813 100644
> --- a/fs/btrfs/bio.c
> +++ b/fs/btrfs/bio.c
> @@ -679,7 +679,8 @@ static bool btrfs_submit_chunk(struct btrfs_bio *bbio, int mirror_num)
>  	blk_status_t ret;
>  	int error;
>  
> -	smap.rst_search_commit_root = !bbio->inode;
> +	smap.rst_search_commit_root =
> +		(!bbio->inode || btrfs_is_data_reloc_root(inode->root));

Please use an 'if' here

Re: [PATCH v3 4/5] btrfs: don't readahead the relocation inode on RST

[David Sterba]

On Wed, Jul 31, 2024 at 10:43:06PM +0200, Johannes Thumshirn wrote:
> From: Johannes Thumshirn <jthumshirn@wdc.com>
> 
> On relocation we're doing readahead on the relocation inode, but if the
> filesystem is backed by a RAID stripe tree we can get ENOENT (e.g. due to
> preallocated extents not being mapped in the RST) from the lookup.
> 
> But readahead doesn't handle the error and submits invalid reads to the
> device, causing an assertion in the scatter-gather list code:
> 
>   BTRFS info (device nvme1n1): balance: start -d -m -s
>   BTRFS info (device nvme1n1): relocating block group 6480920576 flags data|raid0
>   BTRFS error (device nvme1n1): cannot find raid-stripe for logical [6481928192, 6481969152] devid 2, profile raid0
>   ------------[ cut here ]------------
>   kernel BUG at include/linux/scatterlist.h:115!
>   Oops: invalid opcode: 0000 [#1] PREEMPT SMP PTI
>   CPU: 0 PID: 1012 Comm: btrfs Not tainted 6.10.0-rc7+ #567
>   RIP: 0010:__blk_rq_map_sg+0x339/0x4a0
>   RSP: 0018:ffffc90001a43820 EFLAGS: 00010202
>   RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffea00045d4802
>   RDX: 0000000117520000 RSI: 0000000000000000 RDI: ffff8881027d1000
>   RBP: 0000000000003000 R08: ffffea00045d4902 R09: 0000000000000000
>   R10: 0000000000000000 R11: 0000000000001000 R12: ffff8881003d10b8
>   R13: ffffc90001a438f0 R14: 0000000000000000 R15: 0000000000003000
>   FS:  00007fcc048a6900(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000
>   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>   CR2: 000000002cd11000 CR3: 00000001109ea001 CR4: 0000000000370eb0
>   Call Trace:
>    <TASK>
>    ? __die_body.cold+0x14/0x25
>    ? die+0x2e/0x50
>    ? do_trap+0xca/0x110
>    ? do_error_trap+0x65/0x80
>    ? __blk_rq_map_sg+0x339/0x4a0
>    ? exc_invalid_op+0x50/0x70
>    ? __blk_rq_map_sg+0x339/0x4a0
>    ? asm_exc_invalid_op+0x1a/0x20
>    ? __blk_rq_map_sg+0x339/0x4a0
>    nvme_prep_rq.part.0+0x9d/0x770
>    nvme_queue_rq+0x7d/0x1e0
>    __blk_mq_issue_directly+0x2a/0x90
>    ? blk_mq_get_budget_and_tag+0x61/0x90
>    blk_mq_try_issue_list_directly+0x56/0xf0
>    blk_mq_flush_plug_list.part.0+0x52b/0x5d0
>    __blk_flush_plug+0xc6/0x110
>    blk_finish_plug+0x28/0x40
>    read_pages+0x160/0x1c0
>    page_cache_ra_unbounded+0x109/0x180
>    relocate_file_extent_cluster+0x611/0x6a0
>    ? btrfs_search_slot+0xba4/0xd20
>    ? balance_dirty_pages_ratelimited_flags+0x26/0xb00
>    relocate_data_extent.constprop.0+0x134/0x160
>    relocate_block_group+0x3f2/0x500
>    btrfs_relocate_block_group+0x250/0x430
>    btrfs_relocate_chunk+0x3f/0x130
>    btrfs_balance+0x71b/0xef0
>    ? kmalloc_trace_noprof+0x13b/0x280
>    btrfs_ioctl+0x2c2e/0x3030
>    ? kvfree_call_rcu+0x1e6/0x340
>    ? list_lru_add_obj+0x66/0x80
>    ? mntput_no_expire+0x3a/0x220
>    __x64_sys_ioctl+0x96/0xc0
>    do_syscall_64+0x54/0x110
>    entry_SYSCALL_64_after_hwframe+0x76/0x7e
>   RIP: 0033:0x7fcc04514f9b
>   Code: Unable to access opcode bytes at 0x7fcc04514f71.
>   RSP: 002b:00007ffeba923370 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
>   RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fcc04514f9b
>   RDX: 00007ffeba923460 RSI: 00000000c4009420 RDI: 0000000000000003
>   RBP: 0000000000000000 R08: 0000000000000013 R09: 0000000000000001
>   R10: 00007fcc043fbba8 R11: 0000000000000246 R12: 00007ffeba924fc5
>   R13: 00007ffeba923460 R14: 0000000000000002 R15: 00000000004d4bb0
>    </TASK>
>   Modules linked in:
>   ---[ end trace 0000000000000000 ]---
>   RIP: 0010:__blk_rq_map_sg+0x339/0x4a0
>   RSP: 0018:ffffc90001a43820 EFLAGS: 00010202
>   RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffea00045d4802
>   RDX: 0000000117520000 RSI: 0000000000000000 RDI: ffff8881027d1000
>   RBP: 0000000000003000 R08: ffffea00045d4902 R09: 0000000000000000
>   R10: 0000000000000000 R11: 0000000000001000 R12: ffff8881003d10b8
>   R13: ffffc90001a438f0 R14: 0000000000000000 R15: 0000000000003000
>   FS:  00007fcc048a6900(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000
>   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>   CR2: 00007fcc04514f71 CR3: 00000001109ea001 CR4: 0000000000370eb0
>   Kernel panic - not syncing: Fatal exception
>   Kernel Offset: disabled
>   ---[ end Kernel panic - not syncing: Fatal exception ]---
> 
> So in case of a relocation on a RAID stripe-tree based file system, skip
> the readahead.
> 
> Cc: Josef Bacik <josef@toxicpanda.com>
> Cc: Filipe Manana <fdmanana@suse.com>
> Reviewed-by: Josef Bacik <josef@toxicpanda.com>
> Reviewed-by: Qu Wenruo <wqu@suse.com>
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> ---
>  fs/btrfs/relocation.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
> index 0533d0f82dc9..72fb43b4d27c 100644
> --- a/fs/btrfs/relocation.c
> +++ b/fs/btrfs/relocation.c
> @@ -36,6 +36,7 @@
>  #include "relocation.h"
>  #include "super.h"
>  #include "tree-checker.h"
> +#include "raid-stripe-tree.h"
>  
>  /*
>   * Relocation overview
> @@ -2965,21 +2966,26 @@ static int relocate_one_folio(struct reloc_control *rc,
>  	u64 folio_end;
>  	u64 cur;
>  	int ret;
> +	bool use_rst =

	const bool

> +		btrfs_need_stripe_tree_update(fs_info, rc->block_group->flags);
>  
>  	ASSERT(index <= last_index);
>  	folio = filemap_lock_folio(inode->i_mapping, index);
>  	if (IS_ERR(folio)) {
> -		page_cache_sync_readahead(inode->i_mapping, ra, NULL,
> -					  index, last_index + 1 - index);
> +		if (!use_rst)
> +			page_cache_sync_readahead(inode->i_mapping, ra, NULL,

Please add a comment why readahead is skipped for RST (along the lines
in the changelog).