| Message ID | 20170705033307.8213-1-rgoldwyn@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Jul 04, 2017 at 10:33:07PM -0500, Goldwyn Rodrigues wrote: > From: Goldwyn Rodrigues <rgoldwyn@suse.com> > > Assigning pos for usage early messes up in append mode, where > the pos is re-assigned in generic_write_checks(). Assign > pos later to get the correct position to write from iocb->ki_pos. > > Since check_can_nocow also uses the value of pos, we shift > generic_write_checks() before check_can_nocow(). Checks with > IOCB_DIRECT are present in generic_write_checks(), so checking > for IOCB_NOWAIT is enough. > > Also, put locking sequence in the fast path. > > Changes since v1: > - Moved pos higher up to encompass check_can_nocow() call. > > Fixes: edf064e7c6fe ("btrfs: nowait aio support") > Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com> Acked-by: David Sterba <dsterba@suse.com>
On Tue, Jul 04, 2017 at 10:33:07PM -0500, Goldwyn Rodrigues wrote: > From: Goldwyn Rodrigues <rgoldwyn@suse.com> > > Assigning pos for usage early messes up in append mode, where > the pos is re-assigned in generic_write_checks(). Assign > pos later to get the correct position to write from iocb->ki_pos. > > Since check_can_nocow also uses the value of pos, we shift > generic_write_checks() before check_can_nocow(). Checks with > IOCB_DIRECT are present in generic_write_checks(), so checking > for IOCB_NOWAIT is enough. > > Also, put locking sequence in the fast path. > > Changes since v1: > - Moved pos higher up to encompass check_can_nocow() call. > > Fixes: edf064e7c6fe ("btrfs: nowait aio support") > Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com> > --- > fs/btrfs/file.c | 26 ++++++++++++++------------ > 1 file changed, 14 insertions(+), 12 deletions(-) > > diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c > index 59e2dccdf75b..ad53832838b5 100644 > --- a/fs/btrfs/file.c > +++ b/fs/btrfs/file.c > @@ -1875,16 +1875,25 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb, > ssize_t num_written = 0; > bool sync = (file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host); > ssize_t err; > - loff_t pos = iocb->ki_pos; > + loff_t pos; > size_t count = iov_iter_count(from); > loff_t oldsize; > int clean_page = 0; > > - if ((iocb->ki_flags & IOCB_NOWAIT) && > - (iocb->ki_flags & IOCB_DIRECT)) { > - /* Don't sleep on inode rwsem */ > - if (!inode_trylock(inode)) > + if (!inode_trylock(inode)) { > + if (iocb->ki_flags & IOCB_NOWAIT) > return -EAGAIN; > + inode_lock(inode); > + } > + > + err = generic_write_checks(iocb, from); > + if (err <= 0) { > + inode_unlock(inode); > + return err; > + } > + > + pos = iocb->ki_pos; > + if (iocb->ki_flags & IOCB_NOWAIT) { > /* > * We will allocate space in case nodatacow is not set, > * so bail > @@ -1895,13 +1904,6 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb, > inode_unlock(inode); > return -EAGAIN; > } > - } else > - inode_lock(inode); > - > - err = generic_write_checks(iocb, from); > - if (err <= 0) { > - inode_unlock(inode); > - return err; > } > > current->backing_dev_info = inode_to_bdi(inode); Reviewed-by: Liu Bo <bo.li.liu@oracle.com> -liubo
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 59e2dccdf75b..ad53832838b5 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1875,16 +1875,25 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb, ssize_t num_written = 0; bool sync = (file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host); ssize_t err; - loff_t pos = iocb->ki_pos; + loff_t pos; size_t count = iov_iter_count(from); loff_t oldsize; int clean_page = 0; - if ((iocb->ki_flags & IOCB_NOWAIT) && - (iocb->ki_flags & IOCB_DIRECT)) { - /* Don't sleep on inode rwsem */ - if (!inode_trylock(inode)) + if (!inode_trylock(inode)) { + if (iocb->ki_flags & IOCB_NOWAIT) return -EAGAIN; + inode_lock(inode); + } + + err = generic_write_checks(iocb, from); + if (err <= 0) { + inode_unlock(inode); + return err; + } + + pos = iocb->ki_pos; + if (iocb->ki_flags & IOCB_NOWAIT) { /* * We will allocate space in case nodatacow is not set, * so bail @@ -1895,13 +1904,6 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb, inode_unlock(inode); return -EAGAIN; } - } else - inode_lock(inode); - - err = generic_write_checks(iocb, from); - if (err <= 0) { - inode_unlock(inode); - return err; } current->backing_dev_info = inode_to_bdi(inode);