| Message ID | 41a1cc8519061dde7a7cbf2139f672d433a5cfbd.1536331604.git.dsterba@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Cleanup dev-replace locking | expand |
On Fri, Sep 07, 2018 at 04:55:11PM +0200, David Sterba wrote: > The exit sequence in btrfs_dev_replace_start does not allow to simply > add a label to the right place so the error handling after starting > transaction failure jumps there. Currently there's a lock that pairs > with the unlock in the section, which is unnecessary and only raises > questions. Add a variable to track the locking status and avoid the > extra locking. Reviewed-by: Omar Sandoval <osandov@fb.com> > Signed-off-by: David Sterba <dsterba@suse.com> > --- > fs/btrfs/dev-replace.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c > index 8b512dddf727..0a49843b2ee6 100644 > --- a/fs/btrfs/dev-replace.c > +++ b/fs/btrfs/dev-replace.c > @@ -400,6 +400,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, > int ret; > struct btrfs_device *tgt_device = NULL; > struct btrfs_device *src_device = NULL; > + bool need_unlock; > > ret = btrfs_find_device_by_devspec(fs_info, srcdevid, > srcdev_name, &src_device); > @@ -424,6 +425,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, > return PTR_ERR(trans); > } > > + need_unlock = true; > btrfs_dev_replace_write_lock(dev_replace); > switch (dev_replace->replace_state) { > case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED: > @@ -462,6 +464,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, > atomic64_set(&dev_replace->num_write_errors, 0); > atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0); > btrfs_dev_replace_write_unlock(dev_replace); > + need_unlock = false; > > ret = btrfs_sysfs_add_device_link(tgt_device->fs_devices, tgt_device); > if (ret) > @@ -473,7 +476,6 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, > trans = btrfs_start_transaction(root, 0); > if (IS_ERR(trans)) { > ret = PTR_ERR(trans); > - btrfs_dev_replace_write_lock(dev_replace); > goto leave; > } > > @@ -497,7 +499,8 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, > leave: > dev_replace->srcdev = NULL; > dev_replace->tgtdev = NULL; > - btrfs_dev_replace_write_unlock(dev_replace); > + if (need_unlock) > + btrfs_dev_replace_write_unlock(dev_replace); > btrfs_destroy_dev_replace_tgtdev(tgt_device); > return ret; > } > -- > 2.18.0 >
On Fri, Sep 07, 2018 at 04:55:11PM +0200, David Sterba wrote: > The exit sequence in btrfs_dev_replace_start does not allow to simply > add a label to the right place so the error handling after starting > transaction failure jumps there. Currently there's a lock that pairs > with the unlock in the section, which is unnecessary and only raises > questions. Add a variable to track the locking status and avoid the > extra locking. > > Signed-off-by: David Sterba <dsterba@suse.com> > --- > fs/btrfs/dev-replace.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c > index 8b512dddf727..0a49843b2ee6 100644 > --- a/fs/btrfs/dev-replace.c > +++ b/fs/btrfs/dev-replace.c > @@ -400,6 +400,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, > int ret; > struct btrfs_device *tgt_device = NULL; > struct btrfs_device *src_device = NULL; > + bool need_unlock; > > ret = btrfs_find_device_by_devspec(fs_info, srcdevid, > srcdev_name, &src_device); > @@ -424,6 +425,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, > return PTR_ERR(trans); > } > > + need_unlock = true; > btrfs_dev_replace_write_lock(dev_replace); > switch (dev_replace->replace_state) { > case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED: > @@ -462,6 +464,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, > atomic64_set(&dev_replace->num_write_errors, 0); > atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0); > btrfs_dev_replace_write_unlock(dev_replace); > + need_unlock = false; > > ret = btrfs_sysfs_add_device_link(tgt_device->fs_devices, tgt_device); > if (ret) > @@ -473,7 +476,6 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, > trans = btrfs_start_transaction(root, 0); > if (IS_ERR(trans)) { > ret = PTR_ERR(trans); > - btrfs_dev_replace_write_lock(dev_replace); There's a merge conflict with Jeff's patch https://patchwork.kernel.org/patch/10591003/ that adds some dev-replace state change, so the lock must be here. I'll update my patch to @@ -474,6 +477,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, trans = btrfs_start_transaction(root, 0); if (IS_ERR(trans)) { ret = PTR_ERR(trans); + need_unlock = true; btrfs_dev_replace_write_lock(dev_replace); dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED; ---
diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c index 8b512dddf727..0a49843b2ee6 100644 --- a/fs/btrfs/dev-replace.c +++ b/fs/btrfs/dev-replace.c @@ -400,6 +400,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, int ret; struct btrfs_device *tgt_device = NULL; struct btrfs_device *src_device = NULL; + bool need_unlock; ret = btrfs_find_device_by_devspec(fs_info, srcdevid, srcdev_name, &src_device); @@ -424,6 +425,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, return PTR_ERR(trans); } + need_unlock = true; btrfs_dev_replace_write_lock(dev_replace); switch (dev_replace->replace_state) { case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED: @@ -462,6 +464,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, atomic64_set(&dev_replace->num_write_errors, 0); atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0); btrfs_dev_replace_write_unlock(dev_replace); + need_unlock = false; ret = btrfs_sysfs_add_device_link(tgt_device->fs_devices, tgt_device); if (ret) @@ -473,7 +476,6 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, trans = btrfs_start_transaction(root, 0); if (IS_ERR(trans)) { ret = PTR_ERR(trans); - btrfs_dev_replace_write_lock(dev_replace); goto leave; } @@ -497,7 +499,8 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info, leave: dev_replace->srcdev = NULL; dev_replace->tgtdev = NULL; - btrfs_dev_replace_write_unlock(dev_replace); + if (need_unlock) + btrfs_dev_replace_write_unlock(dev_replace); btrfs_destroy_dev_replace_tgtdev(tgt_device); return ret; }
The exit sequence in btrfs_dev_replace_start does not allow to simply add a label to the right place so the error handling after starting transaction failure jumps there. Currently there's a lock that pairs with the unlock in the section, which is unnecessary and only raises questions. Add a variable to track the locking status and avoid the extra locking. Signed-off-by: David Sterba <dsterba@suse.com> --- fs/btrfs/dev-replace.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)