From: Jan Kara Subject: Re: [PATCH 04/10] fs: Introduce RWF_NOWAIT Date: Thu, 25 May 2017 10:30:18 +0200 Message-ID: <20170525083018.GE28950@quack2.suse.cz> References: <20170524164150.9492-1-rgoldwyn@suse.de> <20170524164150.9492-5-rgoldwyn@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel@vger.kernel.org, jack@suse.com, hch@infradead.org, linux-block@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, axboe@kernel.dk, linux-api@vger.kernel.org, adam.manzanares@wdc.com, viro@zeniv.linux.org.uk, Goldwyn Rodrigues To: Goldwyn Rodrigues Return-path: Content-Disposition: inline In-Reply-To: <20170524164150.9492-5-rgoldwyn@suse.de> Sender: linux-btrfs-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Wed 24-05-17 11:41:44, Goldwyn Rodrigues wrote: > From: Goldwyn Rodrigues > > RWF_NOWAIT informs kernel to bail out if an AIO request will block > for reasons such as file allocations, or a writeback triggered, > or would block while allocating requests while performing > direct I/O. > > RWF_NOWAIT is translated to IOCB_NOWAIT for iocb->ki_flags. > > The check for -EOPNOTSUPP is placed in generic_file_write_iter(). This > is called by most filesystems, either through fsops.write_iter() or through > the function defined by write_iter(). If not, we perform the check defined > by .write_iter() which is called for direct IO specifically. > > Filesystems xfs, btrfs and ext4 would be supported in the following patches. > > Signed-off-by: Goldwyn Rodrigues > Reviewed-by: Christoph Hellwig Looks good now. You can add: Reviewed-by: Jan Kara Honza > --- > fs/9p/vfs_file.c | 3 +++ > fs/aio.c | 13 +++++++++++++ > fs/ceph/file.c | 3 +++ > fs/cifs/file.c | 3 +++ > fs/fuse/file.c | 3 +++ > fs/nfs/direct.c | 3 +++ > fs/ocfs2/file.c | 3 +++ > include/linux/fs.h | 5 ++++- > include/uapi/linux/fs.h | 1 + > mm/filemap.c | 3 +++ > 10 files changed, 39 insertions(+), 1 deletion(-) > > diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c > index 3de3b4a89d89..403681db7723 100644 > --- a/fs/9p/vfs_file.c > +++ b/fs/9p/vfs_file.c > @@ -411,6 +411,9 @@ v9fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from) > loff_t origin; > int err = 0; > > + if (iocb->ki_flags & IOCB_NOWAIT) > + return -EOPNOTSUPP; > + > retval = generic_write_checks(iocb, from); > if (retval <= 0) > return retval; > diff --git a/fs/aio.c b/fs/aio.c > index 020fa0045e3c..9616dc733103 100644 > --- a/fs/aio.c > +++ b/fs/aio.c > @@ -1592,6 +1592,19 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, > goto out_put_req; > } > > + if (req->common.ki_flags & IOCB_NOWAIT) { > + if (!(req->common.ki_flags & IOCB_DIRECT)) { > + ret = -EOPNOTSUPP; > + goto out_put_req; > + } > + > + if ((iocb->aio_lio_opcode != IOCB_CMD_PWRITE) && > + (iocb->aio_lio_opcode != IOCB_CMD_PWRITEV)) { > + ret = -EINVAL; > + goto out_put_req; > + } > + } > + > ret = put_user(KIOCB_KEY, &user_iocb->aio_key); > if (unlikely(ret)) { > pr_debug("EFAULT: aio_key\n"); > diff --git a/fs/ceph/file.c b/fs/ceph/file.c > index 3fdde0b283c9..a53fd2675b1b 100644 > --- a/fs/ceph/file.c > +++ b/fs/ceph/file.c > @@ -1300,6 +1300,9 @@ static ssize_t ceph_write_iter(struct kiocb *iocb, struct iov_iter *from) > int err, want, got; > loff_t pos; > > + if (iocb->ki_flags & IOCB_NOWAIT) > + return -EOPNOTSUPP; > + > if (ceph_snap(inode) != CEPH_NOSNAP) > return -EROFS; > > diff --git a/fs/cifs/file.c b/fs/cifs/file.c > index 0fd081bd2a2f..ff84fa9ddb6c 100644 > --- a/fs/cifs/file.c > +++ b/fs/cifs/file.c > @@ -2725,6 +2725,9 @@ ssize_t cifs_user_writev(struct kiocb *iocb, struct iov_iter *from) > * write request. > */ > > + if (iocb->ki_flags & IOCB_NOWAIT) > + return -EOPNOTSUPP; > + > rc = generic_write_checks(iocb, from); > if (rc <= 0) > return rc; > diff --git a/fs/fuse/file.c b/fs/fuse/file.c > index 3ee4fdc3da9e..812c7bd0c290 100644 > --- a/fs/fuse/file.c > +++ b/fs/fuse/file.c > @@ -1425,6 +1425,9 @@ static ssize_t fuse_direct_write_iter(struct kiocb *iocb, struct iov_iter *from) > struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(file); > ssize_t res; > > + if (iocb->ki_flags & IOCB_NOWAIT) > + return -EOPNOTSUPP; > + > if (is_bad_inode(inode)) > return -EIO; > > diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c > index 6fb9fad2d1e6..c8e7dd76126c 100644 > --- a/fs/nfs/direct.c > +++ b/fs/nfs/direct.c > @@ -979,6 +979,9 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter) > dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n", > file, iov_iter_count(iter), (long long) iocb->ki_pos); > > + if (iocb->ki_flags & IOCB_NOWAIT) > + return -EOPNOTSUPP; > + > result = generic_write_checks(iocb, iter); > if (result <= 0) > return result; > diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c > index bfeb647459d9..e7f8ba890305 100644 > --- a/fs/ocfs2/file.c > +++ b/fs/ocfs2/file.c > @@ -2235,6 +2235,9 @@ static ssize_t ocfs2_file_write_iter(struct kiocb *iocb, > if (count == 0) > return 0; > > + if (iocb->ki_flags & IOCB_NOWAIT) > + return -EOPNOTSUPP; > + > direct_io = iocb->ki_flags & IOCB_DIRECT ? 1 : 0; > > inode_lock(inode); > diff --git a/include/linux/fs.h b/include/linux/fs.h > index dc0ab585cd56..2a7d14af6d12 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -268,6 +268,7 @@ struct writeback_control; > #define IOCB_DSYNC (1 << 4) > #define IOCB_SYNC (1 << 5) > #define IOCB_WRITE (1 << 6) > +#define IOCB_NOWAIT (1 << 7) > > struct kiocb { > struct file *ki_filp; > @@ -3060,7 +3061,7 @@ static inline int iocb_flags(struct file *file) > > static inline int kiocb_set_rw_flags(struct kiocb *ki, int flags) > { > - if (unlikely(flags & ~(RWF_HIPRI | RWF_DSYNC | RWF_SYNC))) > + if (unlikely(flags & ~(RWF_HIPRI | RWF_DSYNC | RWF_SYNC | RWF_NOWAIT))) > return -EOPNOTSUPP; > > if (flags & RWF_HIPRI) > @@ -3069,6 +3070,8 @@ static inline int kiocb_set_rw_flags(struct kiocb *ki, int flags) > ki->ki_flags |= IOCB_DSYNC; > if (flags & RWF_SYNC) > ki->ki_flags |= (IOCB_DSYNC | IOCB_SYNC); > + if (flags & RWF_NOWAIT) > + ki->ki_flags |= IOCB_NOWAIT; > return 0; > } > > diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h > index 24e61a54feaa..29969fb7f9a7 100644 > --- a/include/uapi/linux/fs.h > +++ b/include/uapi/linux/fs.h > @@ -360,5 +360,6 @@ struct fscrypt_key { > #define RWF_HIPRI 0x00000001 /* high priority request, poll if possible */ > #define RWF_DSYNC 0x00000002 /* per-IO O_DSYNC */ > #define RWF_SYNC 0x00000004 /* per-IO O_SYNC */ > +#define RWF_NOWAIT 0x00000008 /* per-IO, return -EAGAIN if operation would block */ > > #endif /* _UAPI_LINUX_FS_H */ > diff --git a/mm/filemap.c b/mm/filemap.c > index 87aba7698584..097213275461 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -3006,6 +3006,9 @@ ssize_t generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from) > struct inode *inode = file->f_mapping->host; > ssize_t ret; > > + if (iocb->ki_flags & IOCB_NOWAIT) > + return -EOPNOTSUPP; > + > inode_lock(inode); > ret = generic_write_checks(iocb, from); > if (ret > 0) > -- > 2.12.0 > -- Jan Kara SUSE Labs, CR