| Message ID | 20170509122219.31756-3-rgoldwyn@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, May 09, 2017 at 07:22:13AM -0500, Goldwyn Rodrigues wrote: > From: Goldwyn Rodrigues <rgoldwyn@suse.com> > > This flag 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. > > Unfortunately, aio_flags is not checked for validity, which would > break existing applications which have it set to anything besides zero > or IOCB_FLAG_RESFD. So, we are using aio_reserved1 and renaming it > to aio_rw_flags. > > 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 <rgoldwyn@suse.com> > --- > fs/9p/vfs_file.c | 3 +++ > fs/aio.c | 6 ++++++ > 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, 32 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..ea9f8581d902 100644 > --- a/fs/aio.c > +++ b/fs/aio.c > @@ -1592,6 +1592,12 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, > goto out_put_req; > } > > + if ((req->common.ki_flags & IOCB_NOWAIT) && > + !(req->common.ki_flags & IOCB_DIRECT)) { Weird indentation. Either align after the opening if brace: if ((req->common.ki_flags & IOCB_NOWAIT) && !(req->common.ki_flags & IOCB_DIRECT)) { or using two tabs: if ((req->common.ki_flags & IOCB_NOWAIT) && !(req->common.ki_flags & IOCB_DIRECT)) { if the first version looks confusing, but never using the same indentation level as the following code. Except for that the patch looks fine to me: Reviewed-by: Christoph Hellwig <hch@lst.de>
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..ea9f8581d902 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -1592,6 +1592,12 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, goto out_put_req; } + if ((req->common.ki_flags & IOCB_NOWAIT) && + !(req->common.ki_flags & IOCB_DIRECT)) { + ret = -EOPNOTSUPP; + 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 26cc95421cca..af28419b1731 100644 --- a/fs/ceph/file.c +++ b/fs/ceph/file.c @@ -1267,6 +1267,9 @@ 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 21d404535739..f8858a06e119 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -2638,6 +2638,9 @@ 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 ec238fb5a584..72786e798319 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 c1b5fed7c863..dcea0caa5cb5 100644 --- a/fs/nfs/direct.c +++ b/fs/nfs/direct.c @@ -996,6 +996,9 @@ 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 869c9a6fe58d..4cb62e032b70 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -270,6 +270,7 @@ 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; @@ -3051,7 +3052,7 @@ 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) @@ -3060,6 +3061,8 @@ 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 048a85e9f017..7bcaef101876 100644 --- a/include/uapi/linux/fs.h +++ b/include/uapi/linux/fs.h @@ -347,5 +347,6 @@ struct fscrypt_policy { #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 1694623a6289..d51670b7fe6b 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2982,6 +2982,9 @@ 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)