From mboxrd@z Thu Jan 1 00:00:00 1970 From: Goldwyn Rodrigues Subject: [PATCH 2/8] nowait aio: Introduce RWF_NOWAIT Date: Fri, 14 Apr 2017 07:02:51 -0500 Message-ID: <20170414120257.8932-3-rgoldwyn@suse.de> References: <20170414120257.8932-1-rgoldwyn@suse.de> Return-path: In-Reply-To: <20170414120257.8932-1-rgoldwyn@suse.de> Sender: linux-block-owner@vger.kernel.org To: linux-fsdevel@vger.kernel.org Cc: 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, sagi@grimberg.me, avi@scylladb.com, axboe@kernel.dk, linux-api@vger.kernel.org, willy@infradead.org, tom.leiming@gmail.com, Goldwyn Rodrigues List-Id: linux-api@vger.kernel.org From: Goldwyn Rodrigues 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 --- fs/9p/vfs_file.c | 3 +++ fs/aio.c | 9 +++++++-- 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 +++ fs/read_write.c | 2 +- include/linux/fs.h | 3 +++ include/uapi/linux/fs.h | 1 + mm/filemap.c | 3 +++ 11 files changed, 33 insertions(+), 3 deletions(-) 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 b8a33f5beef5..d3b5c8dc6549 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -1546,12 +1546,12 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, return -EINVAL; } - if (unlikely(iocb->aio_rw_flags & ~(RWF_HIPRI | RWF_DSYNC | RWF_SYNC))) { + if (unlikely(iocb->aio_rw_flags & + ~(RWF_HIPRI | RWF_DSYNC | RWF_SYNC | RWF_NOWAIT))) { pr_debug("EINVAL: aio_rw_flags set with incompatible flags\n"); return -EINVAL; } - /* prevent overflows */ if (unlikely( (iocb->aio_buf != (unsigned long)iocb->aio_buf) || @@ -1593,6 +1593,11 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, } req->common.ki_flags |= iocb_rw_flags(iocb->aio_rw_flags); + if ((req->common.ki_flags & IOCB_NOWAIT) && + !(req->common.ki_flags & IOCB_DIRECT)) { + ret = -EINVAL; + goto out_put_req; + } ret = put_user(KIOCB_KEY, &user_iocb->aio_key); if (unlikely(ret)) { 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 aa3debbba826..a828ab3e7775 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 aab32fc3d6a8..ab419caebd5f 100644 --- a/fs/nfs/direct.c +++ b/fs/nfs/direct.c @@ -991,6 +991,9 @@ 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/fs/read_write.c b/fs/read_write.c index 9aa557bb471c..97f3d6d444b8 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -678,7 +678,7 @@ static ssize_t do_iter_readv_writev(struct file *filp, struct iov_iter *iter, struct kiocb kiocb; ssize_t ret; - if (flags & ~(RWF_HIPRI | RWF_DSYNC | RWF_SYNC)) + if (flags & ~(RWF_HIPRI | RWF_DSYNC | RWF_SYNC | RWF_NOWAIT)) return -EOPNOTSUPP; init_sync_kiocb(&kiocb, filp); diff --git a/include/linux/fs.h b/include/linux/fs.h index 35cfb08ceb9d..e44de1c981a0 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; @@ -3058,6 +3059,8 @@ static inline int iocb_rw_flags(int flags) res |= IOCB_DSYNC; if (flags & RWF_SYNC) res |= (IOCB_DSYNC | IOCB_SYNC); + if (flags & RWF_NOWAIT) + res |= IOCB_NOWAIT; return res; } 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) -- 2.12.0