| Message ID | 20190606075444.15481-1-naohiro.aota@wdc.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | btrfs: start readahead also in seed devices | expand |
On Thu, Jun 6, 2019 at 8:56 AM Naohiro Aota <naohiro.aota@wdc.com> wrote: > > Currently, btrfs does not consult seed devices to start readahead. As a > result, if readahead zone is added to the seed devices, btrfs_reada_wait() > indefinitely wait for the reada_ctl to finish. > > You can reproduce the hung by modifying btrfs/163 to have larger initial > file size (e.g. xfs_io pwrite 4M instead of current 256K). Are you planning on submitting a patch for the test case as well, so that it writes at least 4Mb? Would be useful to have. > > Fixes: 7414a03fbf9e ("btrfs: initial readahead code and prototypes") > Cc: stable@vger.kernel.org # 3.2+: ce7791ffee1e: Btrfs: fix race between readahead and device replace/removal > Cc: stable@vger.kernel.org # 3.2+ > Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com> Reviewed-by: Filipe Manana <fdmanana@suse.com> Looks good, thanks. > --- > fs/btrfs/reada.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c > index 10d9589001a9..bb5bd49573b4 100644 > --- a/fs/btrfs/reada.c > +++ b/fs/btrfs/reada.c > @@ -747,6 +747,7 @@ static void __reada_start_machine(struct btrfs_fs_info *fs_info) > u64 total = 0; > int i; > > +again: > do { > enqueued = 0; > mutex_lock(&fs_devices->device_list_mutex); > @@ -758,6 +759,10 @@ static void __reada_start_machine(struct btrfs_fs_info *fs_info) > mutex_unlock(&fs_devices->device_list_mutex); > total += enqueued; > } while (enqueued && total < 10000); > + if (fs_devices->seed) { > + fs_devices = fs_devices->seed; > + goto again; > + } > > if (enqueued == 0) > return; > -- > 2.21.0 >
On 2019/06/06 20:14, Filipe Manana wrote: > On Thu, Jun 6, 2019 at 8:56 AM Naohiro Aota <naohiro.aota@wdc.com> wrote: >> >> Currently, btrfs does not consult seed devices to start readahead. As a >> result, if readahead zone is added to the seed devices, btrfs_reada_wait() >> indefinitely wait for the reada_ctl to finish. >> >> You can reproduce the hung by modifying btrfs/163 to have larger initial >> file size (e.g. xfs_io pwrite 4M instead of current 256K). > > Are you planning on submitting a patch for the test case as well, so > that it writes at least 4Mb? > Would be useful to have. I will send that patch soon. Thanks, > >> >> Fixes: 7414a03fbf9e ("btrfs: initial readahead code and prototypes") >> Cc: stable@vger.kernel.org # 3.2+: ce7791ffee1e: Btrfs: fix race between readahead and device replace/removal >> Cc: stable@vger.kernel.org # 3.2+ >> Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com> > > Reviewed-by: Filipe Manana <fdmanana@suse.com> > > Looks good, thanks. > >> --- >> fs/btrfs/reada.c | 5 +++++ >> 1 file changed, 5 insertions(+) >> >> diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c >> index 10d9589001a9..bb5bd49573b4 100644 >> --- a/fs/btrfs/reada.c >> +++ b/fs/btrfs/reada.c >> @@ -747,6 +747,7 @@ static void __reada_start_machine(struct btrfs_fs_info *fs_info) >> u64 total = 0; >> int i; >> >> +again: >> do { >> enqueued = 0; >> mutex_lock(&fs_devices->device_list_mutex); >> @@ -758,6 +759,10 @@ static void __reada_start_machine(struct btrfs_fs_info *fs_info) >> mutex_unlock(&fs_devices->device_list_mutex); >> total += enqueued; >> } while (enqueued && total < 10000); >> + if (fs_devices->seed) { >> + fs_devices = fs_devices->seed; >> + goto again; >> + } >> >> if (enqueued == 0) >> return; >> -- >> 2.21.0 >> > >
On Thu, Jun 06, 2019 at 04:54:44PM +0900, Naohiro Aota wrote: > Currently, btrfs does not consult seed devices to start readahead. As a > result, if readahead zone is added to the seed devices, btrfs_reada_wait() > indefinitely wait for the reada_ctl to finish. > > You can reproduce the hung by modifying btrfs/163 to have larger initial > file size (e.g. xfs_io pwrite 4M instead of current 256K). > > Fixes: 7414a03fbf9e ("btrfs: initial readahead code and prototypes") > Cc: stable@vger.kernel.org # 3.2+: ce7791ffee1e: Btrfs: fix race between readahead and device replace/removal > Cc: stable@vger.kernel.org # 3.2+ > Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com> Thanks, added to misc-next.
diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c index 10d9589001a9..bb5bd49573b4 100644 --- a/fs/btrfs/reada.c +++ b/fs/btrfs/reada.c @@ -747,6 +747,7 @@ static void __reada_start_machine(struct btrfs_fs_info *fs_info) u64 total = 0; int i; +again: do { enqueued = 0; mutex_lock(&fs_devices->device_list_mutex); @@ -758,6 +759,10 @@ static void __reada_start_machine(struct btrfs_fs_info *fs_info) mutex_unlock(&fs_devices->device_list_mutex); total += enqueued; } while (enqueued && total < 10000); + if (fs_devices->seed) { + fs_devices = fs_devices->seed; + goto again; + } if (enqueued == 0) return;
Currently, btrfs does not consult seed devices to start readahead. As a result, if readahead zone is added to the seed devices, btrfs_reada_wait() indefinitely wait for the reada_ctl to finish. You can reproduce the hung by modifying btrfs/163 to have larger initial file size (e.g. xfs_io pwrite 4M instead of current 256K). Fixes: 7414a03fbf9e ("btrfs: initial readahead code and prototypes") Cc: stable@vger.kernel.org # 3.2+: ce7791ffee1e: Btrfs: fix race between readahead and device replace/removal Cc: stable@vger.kernel.org # 3.2+ Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com> --- fs/btrfs/reada.c | 5 +++++ 1 file changed, 5 insertions(+)