* [PATCH v2 1/2] btrfs: avoid possible signal interruption for btrfs_drop_snapshot() on relocation tree @ 2020-07-09 8:33 Qu Wenruo 2020-07-09 8:33 ` [PATCH v2 2/2] btrfs: relocation: review the call sites which can be interruped by signal Qu Wenruo 2020-07-09 11:05 ` [PATCH v2 1/2] btrfs: avoid possible signal interruption for btrfs_drop_snapshot() on relocation tree David Sterba 0 siblings, 2 replies; 8+ messages in thread From: Qu Wenruo @ 2020-07-09 8:33 UTC (permalink / raw) To: linux-btrfs; +Cc: Josef Bacik [BUG] There is a bug report about bad signal timing could lead to read-only fs during balance: BTRFS info (device xvdb): balance: start -d -m -s BTRFS info (device xvdb): relocating block group 73001861120 flags metadata BTRFS info (device xvdb): found 12236 extents, stage: move data extents BTRFS info (device xvdb): relocating block group 71928119296 flags data BTRFS info (device xvdb): found 3 extents, stage: move data extents BTRFS info (device xvdb): found 3 extents, stage: update data pointers BTRFS info (device xvdb): relocating block group 60922265600 flags metadata BTRFS: error (device xvdb) in btrfs_drop_snapshot:5505: errno=-4 unknown BTRFS info (device xvdb): forced readonly BTRFS info (device xvdb): balance: ended with status: -4 [CAUSE] The direct cause is the -EINTR from the following call chain when a fatal signal is pending: relocate_block_group() |- clean_dirty_subvols() |- btrfs_drop_snapshot() |- btrfs_start_transaction() |- btrfs_delayed_refs_rsv_refill() |- btrfs_reserve_metadata_bytes() |- __reserve_metadata_bytes() |- wait_reserve_ticket() |- prepare_to_wait_event(); |- ticket->error = -EINTR; Normally this behavior is fine for most btrfs_start_transaction() callers, as they need to catch the fatal signal and exit asap. However for balance, especially for the clean_dirty_subvols() case, we're already doing cleanup works, such -EINTR from btrfs_drop_snapshot() could cause a lot of unexpected problems. From the mentioned forced read-only, to later balance error due to half dropped reloc trees. [FIX] Fix this problem by using btrfs_join_transaction() if btrfs_drop_snapshot() is called from relocation context. As btrfs_join_transaction() won't wait full tickets, it won't get interrupted from signal. Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: Josef Bacik <josef@toxicpanda.com> --- fs/btrfs/extent-tree.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index c0bc35f932bf..d8ef48a807d1 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -5298,7 +5298,10 @@ int btrfs_drop_snapshot(struct btrfs_root *root, int update_ref, int for_reloc) goto out; } - trans = btrfs_start_transaction(tree_root, 0); + if (for_reloc) + trans = btrfs_join_transaction(tree_root); + else + trans = btrfs_start_transaction(tree_root, 0); if (IS_ERR(trans)) { err = PTR_ERR(trans); goto out_free; -- 2.27.0 ^ permalink raw reply related [flat|nested] 8+ messages in thread
* [PATCH v2 2/2] btrfs: relocation: review the call sites which can be interruped by signal 2020-07-09 8:33 [PATCH v2 1/2] btrfs: avoid possible signal interruption for btrfs_drop_snapshot() on relocation tree Qu Wenruo @ 2020-07-09 8:33 ` Qu Wenruo 2020-07-09 9:54 ` David Sterba 2020-07-09 11:05 ` [PATCH v2 1/2] btrfs: avoid possible signal interruption for btrfs_drop_snapshot() on relocation tree David Sterba 1 sibling, 1 reply; 8+ messages in thread From: Qu Wenruo @ 2020-07-09 8:33 UTC (permalink / raw) To: linux-btrfs Since most metadata reservation calls can return -EINTR when get interruped by fatal signal, we need to review the all the metadata reservation call sites. In relocation code, the metadata reservation happens in the following sites: - btrfs_block_rsv_refill() in merge_reloc_root() merge_reloc_root() is a pretty critial section, we don't want get interrupted by signal, so change the flush status to BTRFS_RESERVE_FLUSH_LIMIT, so it won't get interrupted by signal. Since such change can be ENPSPC-prone, also shrink the amount of metadata to reserve a little to avoid deadly ENOSPC there. - btrfs_block_rsv_refill() in reserve_metadata_space() It calls with BTRFS_RESERVE_FLUSH_LIMIT, which won't get interrupred by signal. - btrfs_block_rsv_refill() in prepare_to_relocate() - btrfs_block_rsv_add() in prepare_to_relocate() - btrfs_block_rsv_refill() in relocate_block_group() - btrfs_delalloc_reserve_metadata() in relocate_file_extent_cluster() - btrfs_start_transaction() in relocate_block_group() - btrfs_start_transaction() in create_reloc_inode() Can be interruped by fatal signal and we can handle it easily. For these call sites, just catch the -EINTR value in btrfs_balance() and count them as canceled. Signed-off-by: Qu Wenruo <wqu@suse.com> --- fs/btrfs/relocation.c | 13 +++++++++++-- fs/btrfs/volumes.c | 2 +- 2 files changed, 12 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index 2b869fb2e62c..23914edd4710 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -1686,12 +1686,21 @@ static noinline_for_stack int merge_reloc_root(struct reloc_control *rc, btrfs_unlock_up_safe(path, 0); } - min_reserved = fs_info->nodesize * (BTRFS_MAX_LEVEL - 1) * 2; + /* + * In merge_reloc_root(), we modify the upper level pointer to swap + * the tree blocks between reloc tree and subvolume tree. + * Thus for tree block COW, we COW at most from level 1 to root level + * for each tree. + * + * Thus the needed metadata space is at most root_level * nodesize, + * and * 2 since we have two trees to COW. + */ + min_reserved = fs_info->nodesize * btrfs_root_level(root_item) * 2; memset(&next_key, 0, sizeof(next_key)); while (1) { ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved, - BTRFS_RESERVE_FLUSH_ALL); + BTRFS_RESERVE_FLUSH_LIMIT); if (ret) { err = ret; goto out; diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index aabc6c922e04..d60df30bdc47 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -4135,7 +4135,7 @@ int btrfs_balance(struct btrfs_fs_info *fs_info, mutex_lock(&fs_info->balance_mutex); if (ret == -ECANCELED && atomic_read(&fs_info->balance_pause_req)) btrfs_info(fs_info, "balance: paused"); - else if (ret == -ECANCELED && atomic_read(&fs_info->balance_cancel_req)) + else if (ret == -ECANCELED || ret == -EINTR) btrfs_info(fs_info, "balance: canceled"); else btrfs_info(fs_info, "balance: ended with status: %d", ret); -- 2.27.0 ^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH v2 2/2] btrfs: relocation: review the call sites which can be interruped by signal 2020-07-09 8:33 ` [PATCH v2 2/2] btrfs: relocation: review the call sites which can be interruped by signal Qu Wenruo @ 2020-07-09 9:54 ` David Sterba 2020-07-09 10:15 ` Qu Wenruo 2020-07-09 10:46 ` Qu Wenruo 0 siblings, 2 replies; 8+ messages in thread From: David Sterba @ 2020-07-09 9:54 UTC (permalink / raw) To: Qu Wenruo; +Cc: linux-btrfs On Thu, Jul 09, 2020 at 04:33:33PM +0800, Qu Wenruo wrote: > Since most metadata reservation calls can return -EINTR when get > interruped by fatal signal, we need to review the all the metadata > reservation call sites. > > In relocation code, the metadata reservation happens in the following > sites: > - btrfs_block_rsv_refill() in merge_reloc_root() > merge_reloc_root() is a pretty critial section, we don't want get > interrupted by signal, so change the flush status to > BTRFS_RESERVE_FLUSH_LIMIT, so it won't get interrupted by signal. > Since such change can be ENPSPC-prone, also shrink the amount of > metadata to reserve a little to avoid deadly ENOSPC there. > > - btrfs_block_rsv_refill() in reserve_metadata_space() > It calls with BTRFS_RESERVE_FLUSH_LIMIT, which won't get interrupred > by signal. This semantics of BTRFS_RESERVE_FLUSH_LIMIT regarding signals should be documented, right now there's a comment but says something about avoidig deadlocks. > - btrfs_block_rsv_refill() in prepare_to_relocate() > - btrfs_block_rsv_add() in prepare_to_relocate() > - btrfs_block_rsv_refill() in relocate_block_group() > - btrfs_delalloc_reserve_metadata() in relocate_file_extent_cluster() > - btrfs_start_transaction() in relocate_block_group() > - btrfs_start_transaction() in create_reloc_inode() > Can be interruped by fatal signal and we can handle it easily. > For these call sites, just catch the -EINTR value in btrfs_balance() > and count them as canceled. > > Signed-off-by: Qu Wenruo <wqu@suse.com> > --- > fs/btrfs/relocation.c | 13 +++++++++++-- > fs/btrfs/volumes.c | 2 +- > 2 files changed, 12 insertions(+), 3 deletions(-) > > diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c > index 2b869fb2e62c..23914edd4710 100644 > --- a/fs/btrfs/relocation.c > +++ b/fs/btrfs/relocation.c > @@ -1686,12 +1686,21 @@ static noinline_for_stack int merge_reloc_root(struct reloc_control *rc, > btrfs_unlock_up_safe(path, 0); > } > > - min_reserved = fs_info->nodesize * (BTRFS_MAX_LEVEL - 1) * 2; > + /* > + * In merge_reloc_root(), we modify the upper level pointer to swap > + * the tree blocks between reloc tree and subvolume tree. > + * Thus for tree block COW, we COW at most from level 1 to root level > + * for each tree. > + * > + * Thus the needed metadata space is at most root_level * nodesize, > + * and * 2 since we have two trees to COW. > + */ > + min_reserved = fs_info->nodesize * btrfs_root_level(root_item) * 2; > memset(&next_key, 0, sizeof(next_key)); > > while (1) { > ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved, > - BTRFS_RESERVE_FLUSH_ALL); > + BTRFS_RESERVE_FLUSH_LIMIT); > if (ret) { > err = ret; > goto out; > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c > index aabc6c922e04..d60df30bdc47 100644 > --- a/fs/btrfs/volumes.c > +++ b/fs/btrfs/volumes.c > @@ -4135,7 +4135,7 @@ int btrfs_balance(struct btrfs_fs_info *fs_info, > mutex_lock(&fs_info->balance_mutex); > if (ret == -ECANCELED && atomic_read(&fs_info->balance_pause_req)) > btrfs_info(fs_info, "balance: paused"); > - else if (ret == -ECANCELED && atomic_read(&fs_info->balance_cancel_req)) > + else if (ret == -ECANCELED || ret == -EINTR) Why do you remove atomic_read(&fs_info->balance_cancel_req) ? > btrfs_info(fs_info, "balance: canceled"); I'm not sure if it would be useful to print the reason, like - 'canceled: user request' - 'canceled: interrupted' > else > btrfs_info(fs_info, "balance: ended with status: %d", ret); > -- > 2.27.0 ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2 2/2] btrfs: relocation: review the call sites which can be interruped by signal 2020-07-09 9:54 ` David Sterba @ 2020-07-09 10:15 ` Qu Wenruo 2020-07-09 10:25 ` David Sterba 2020-07-09 10:46 ` Qu Wenruo 1 sibling, 1 reply; 8+ messages in thread From: Qu Wenruo @ 2020-07-09 10:15 UTC (permalink / raw) To: dsterba, linux-btrfs On 2020/7/9 下午5:54, David Sterba wrote: > On Thu, Jul 09, 2020 at 04:33:33PM +0800, Qu Wenruo wrote: >> Since most metadata reservation calls can return -EINTR when get >> interruped by fatal signal, we need to review the all the metadata >> reservation call sites. >> >> In relocation code, the metadata reservation happens in the following >> sites: >> - btrfs_block_rsv_refill() in merge_reloc_root() >> merge_reloc_root() is a pretty critial section, we don't want get >> interrupted by signal, so change the flush status to >> BTRFS_RESERVE_FLUSH_LIMIT, so it won't get interrupted by signal. >> Since such change can be ENPSPC-prone, also shrink the amount of >> metadata to reserve a little to avoid deadly ENOSPC there. >> >> - btrfs_block_rsv_refill() in reserve_metadata_space() >> It calls with BTRFS_RESERVE_FLUSH_LIMIT, which won't get interrupred >> by signal. > > This semantics of BTRFS_RESERVE_FLUSH_LIMIT regarding signals should be > documented, right now there's a comment but says something about avoidig > deadlocks. > >> - btrfs_block_rsv_refill() in prepare_to_relocate() >> - btrfs_block_rsv_add() in prepare_to_relocate() >> - btrfs_block_rsv_refill() in relocate_block_group() >> - btrfs_delalloc_reserve_metadata() in relocate_file_extent_cluster() >> - btrfs_start_transaction() in relocate_block_group() >> - btrfs_start_transaction() in create_reloc_inode() >> Can be interruped by fatal signal and we can handle it easily. >> For these call sites, just catch the -EINTR value in btrfs_balance() >> and count them as canceled. >> >> Signed-off-by: Qu Wenruo <wqu@suse.com> >> --- >> fs/btrfs/relocation.c | 13 +++++++++++-- >> fs/btrfs/volumes.c | 2 +- >> 2 files changed, 12 insertions(+), 3 deletions(-) >> >> diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c >> index 2b869fb2e62c..23914edd4710 100644 >> --- a/fs/btrfs/relocation.c >> +++ b/fs/btrfs/relocation.c >> @@ -1686,12 +1686,21 @@ static noinline_for_stack int merge_reloc_root(struct reloc_control *rc, >> btrfs_unlock_up_safe(path, 0); >> } >> >> - min_reserved = fs_info->nodesize * (BTRFS_MAX_LEVEL - 1) * 2; >> + /* >> + * In merge_reloc_root(), we modify the upper level pointer to swap >> + * the tree blocks between reloc tree and subvolume tree. >> + * Thus for tree block COW, we COW at most from level 1 to root level >> + * for each tree. >> + * >> + * Thus the needed metadata space is at most root_level * nodesize, >> + * and * 2 since we have two trees to COW. >> + */ >> + min_reserved = fs_info->nodesize * btrfs_root_level(root_item) * 2; >> memset(&next_key, 0, sizeof(next_key)); >> >> while (1) { >> ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved, >> - BTRFS_RESERVE_FLUSH_ALL); >> + BTRFS_RESERVE_FLUSH_LIMIT); >> if (ret) { >> err = ret; >> goto out; >> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c >> index aabc6c922e04..d60df30bdc47 100644 >> --- a/fs/btrfs/volumes.c >> +++ b/fs/btrfs/volumes.c >> @@ -4135,7 +4135,7 @@ int btrfs_balance(struct btrfs_fs_info *fs_info, >> mutex_lock(&fs_info->balance_mutex); >> if (ret == -ECANCELED && atomic_read(&fs_info->balance_pause_req)) >> btrfs_info(fs_info, "balance: paused"); >> - else if (ret == -ECANCELED && atomic_read(&fs_info->balance_cancel_req)) >> + else if (ret == -ECANCELED || ret == -EINTR) > > Why do you remove atomic_read(&fs_info->balance_cancel_req) ? Because now btrfs_should_cancel_balance() can return ECANCELED without balance_cancel_req increased due to pending fatal signal. > >> btrfs_info(fs_info, "balance: canceled"); > > I'm not sure if it would be useful to print the reason, like > > - 'canceled: user request' > - 'canceled: interrupted' To me, if user interrupt the balance progress, it's obvious they want to cancel it. Thus no need to distinguish btrfs balance cancel and signal cancel. Thanks, Qu > >> else >> btrfs_info(fs_info, "balance: ended with status: %d", ret); >> -- >> 2.27.0 ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2 2/2] btrfs: relocation: review the call sites which can be interruped by signal 2020-07-09 10:15 ` Qu Wenruo @ 2020-07-09 10:25 ` David Sterba 0 siblings, 0 replies; 8+ messages in thread From: David Sterba @ 2020-07-09 10:25 UTC (permalink / raw) To: Qu Wenruo; +Cc: dsterba, linux-btrfs On Thu, Jul 09, 2020 at 06:15:09PM +0800, Qu Wenruo wrote: > On 2020/7/9 下午5:54, David Sterba wrote: > > On Thu, Jul 09, 2020 at 04:33:33PM +0800, Qu Wenruo wrote: > >> @@ -4135,7 +4135,7 @@ int btrfs_balance(struct btrfs_fs_info *fs_info, > >> mutex_lock(&fs_info->balance_mutex); > >> if (ret == -ECANCELED && atomic_read(&fs_info->balance_pause_req)) > >> btrfs_info(fs_info, "balance: paused"); > >> - else if (ret == -ECANCELED && atomic_read(&fs_info->balance_cancel_req)) > >> + else if (ret == -ECANCELED || ret == -EINTR) > > > > Why do you remove atomic_read(&fs_info->balance_cancel_req) ? > > Because now btrfs_should_cancel_balance() can return ECANCELED without > balance_cancel_req increased due to pending fatal signal. Ah right, I misread it as || which would remove one reason for cancellation. ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2 2/2] btrfs: relocation: review the call sites which can be interruped by signal 2020-07-09 9:54 ` David Sterba 2020-07-09 10:15 ` Qu Wenruo @ 2020-07-09 10:46 ` Qu Wenruo 1 sibling, 0 replies; 8+ messages in thread From: Qu Wenruo @ 2020-07-09 10:46 UTC (permalink / raw) To: dsterba, Qu Wenruo, linux-btrfs [-- Attachment #1.1: Type: text/plain, Size: 4125 bytes --] On 2020/7/9 下午5:54, David Sterba wrote: > On Thu, Jul 09, 2020 at 04:33:33PM +0800, Qu Wenruo wrote: >> Since most metadata reservation calls can return -EINTR when get >> interruped by fatal signal, we need to review the all the metadata >> reservation call sites. >> >> In relocation code, the metadata reservation happens in the following >> sites: >> - btrfs_block_rsv_refill() in merge_reloc_root() >> merge_reloc_root() is a pretty critial section, we don't want get >> interrupted by signal, so change the flush status to >> BTRFS_RESERVE_FLUSH_LIMIT, so it won't get interrupted by signal. >> Since such change can be ENPSPC-prone, also shrink the amount of >> metadata to reserve a little to avoid deadly ENOSPC there. >> >> - btrfs_block_rsv_refill() in reserve_metadata_space() >> It calls with BTRFS_RESERVE_FLUSH_LIMIT, which won't get interrupred >> by signal. > > This semantics of BTRFS_RESERVE_FLUSH_LIMIT regarding signals should be > documented, right now there's a comment but says something about avoidig > deadlocks. For this, I tend to add one or more patches to add some comment for all FLUSH enums, and all their callers. I hate when some infrastructure hit me by surprise, and since ticketing system is hidden from a lot of functions, we also need to mention that -EINTR case. Thanks, Qu > >> - btrfs_block_rsv_refill() in prepare_to_relocate() >> - btrfs_block_rsv_add() in prepare_to_relocate() >> - btrfs_block_rsv_refill() in relocate_block_group() >> - btrfs_delalloc_reserve_metadata() in relocate_file_extent_cluster() >> - btrfs_start_transaction() in relocate_block_group() >> - btrfs_start_transaction() in create_reloc_inode() >> Can be interruped by fatal signal and we can handle it easily. >> For these call sites, just catch the -EINTR value in btrfs_balance() >> and count them as canceled. >> >> Signed-off-by: Qu Wenruo <wqu@suse.com> >> --- >> fs/btrfs/relocation.c | 13 +++++++++++-- >> fs/btrfs/volumes.c | 2 +- >> 2 files changed, 12 insertions(+), 3 deletions(-) >> >> diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c >> index 2b869fb2e62c..23914edd4710 100644 >> --- a/fs/btrfs/relocation.c >> +++ b/fs/btrfs/relocation.c >> @@ -1686,12 +1686,21 @@ static noinline_for_stack int merge_reloc_root(struct reloc_control *rc, >> btrfs_unlock_up_safe(path, 0); >> } >> >> - min_reserved = fs_info->nodesize * (BTRFS_MAX_LEVEL - 1) * 2; >> + /* >> + * In merge_reloc_root(), we modify the upper level pointer to swap >> + * the tree blocks between reloc tree and subvolume tree. >> + * Thus for tree block COW, we COW at most from level 1 to root level >> + * for each tree. >> + * >> + * Thus the needed metadata space is at most root_level * nodesize, >> + * and * 2 since we have two trees to COW. >> + */ >> + min_reserved = fs_info->nodesize * btrfs_root_level(root_item) * 2; >> memset(&next_key, 0, sizeof(next_key)); >> >> while (1) { >> ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved, >> - BTRFS_RESERVE_FLUSH_ALL); >> + BTRFS_RESERVE_FLUSH_LIMIT); >> if (ret) { >> err = ret; >> goto out; >> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c >> index aabc6c922e04..d60df30bdc47 100644 >> --- a/fs/btrfs/volumes.c >> +++ b/fs/btrfs/volumes.c >> @@ -4135,7 +4135,7 @@ int btrfs_balance(struct btrfs_fs_info *fs_info, >> mutex_lock(&fs_info->balance_mutex); >> if (ret == -ECANCELED && atomic_read(&fs_info->balance_pause_req)) >> btrfs_info(fs_info, "balance: paused"); >> - else if (ret == -ECANCELED && atomic_read(&fs_info->balance_cancel_req)) >> + else if (ret == -ECANCELED || ret == -EINTR) > > Why do you remove atomic_read(&fs_info->balance_cancel_req) ? > >> btrfs_info(fs_info, "balance: canceled"); > > I'm not sure if it would be useful to print the reason, like > > - 'canceled: user request' > - 'canceled: interrupted' > >> else >> btrfs_info(fs_info, "balance: ended with status: %d", ret); >> -- >> 2.27.0 [-- Attachment #2: OpenPGP digital signature --] [-- Type: application/pgp-signature, Size: 488 bytes --] ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2 1/2] btrfs: avoid possible signal interruption for btrfs_drop_snapshot() on relocation tree 2020-07-09 8:33 [PATCH v2 1/2] btrfs: avoid possible signal interruption for btrfs_drop_snapshot() on relocation tree Qu Wenruo 2020-07-09 8:33 ` [PATCH v2 2/2] btrfs: relocation: review the call sites which can be interruped by signal Qu Wenruo @ 2020-07-09 11:05 ` David Sterba 2020-07-09 12:11 ` Qu Wenruo 1 sibling, 1 reply; 8+ messages in thread From: David Sterba @ 2020-07-09 11:05 UTC (permalink / raw) To: Qu Wenruo; +Cc: linux-btrfs, Josef Bacik On Thu, Jul 09, 2020 at 04:33:32PM +0800, Qu Wenruo wrote: > From the mentioned forced read-only, to later balance error due to half > dropped reloc trees. > > [FIX] > Fix this problem by using btrfs_join_transaction() if > btrfs_drop_snapshot() is called from relocation context. > > As btrfs_join_transaction() won't wait full tickets, it won't get > interrupted from signal. Could you please rephrase the text above? ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2 1/2] btrfs: avoid possible signal interruption for btrfs_drop_snapshot() on relocation tree 2020-07-09 11:05 ` [PATCH v2 1/2] btrfs: avoid possible signal interruption for btrfs_drop_snapshot() on relocation tree David Sterba @ 2020-07-09 12:11 ` Qu Wenruo 0 siblings, 0 replies; 8+ messages in thread From: Qu Wenruo @ 2020-07-09 12:11 UTC (permalink / raw) To: dsterba, Qu Wenruo, linux-btrfs, Josef Bacik [-- Attachment #1.1: Type: text/plain, Size: 648 bytes --] On 2020/7/9 下午7:05, David Sterba wrote: > On Thu, Jul 09, 2020 at 04:33:32PM +0800, Qu Wenruo wrote: > >> From the mentioned forced read-only, to later balance error due to half >> dropped reloc trees. >> >> [FIX] >> Fix this problem by using btrfs_join_transaction() if >> btrfs_drop_snapshot() is called from relocation context. >> >> As btrfs_join_transaction() won't wait full tickets, it won't get >> interrupted from signal. > > Could you please rephrase the text above? > How about this: As btrfs_join_transaction() won't reserve new metadata space, it won't get interrupted by signal at all. Thanks, Qu [-- Attachment #2: OpenPGP digital signature --] [-- Type: application/pgp-signature, Size: 488 bytes --] ^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2020-07-09 12:12 UTC | newest] Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2020-07-09 8:33 [PATCH v2 1/2] btrfs: avoid possible signal interruption for btrfs_drop_snapshot() on relocation tree Qu Wenruo 2020-07-09 8:33 ` [PATCH v2 2/2] btrfs: relocation: review the call sites which can be interruped by signal Qu Wenruo 2020-07-09 9:54 ` David Sterba 2020-07-09 10:15 ` Qu Wenruo 2020-07-09 10:25 ` David Sterba 2020-07-09 10:46 ` Qu Wenruo 2020-07-09 11:05 ` [PATCH v2 1/2] btrfs: avoid possible signal interruption for btrfs_drop_snapshot() on relocation tree David Sterba 2020-07-09 12:11 ` Qu Wenruo
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