[PATCH 04/10] fs: Introduce RWF_NOWAIT and FMODE_AIO_NOWAIT
From: Goldwyn Rodrigues <hidden>
Date: 2017-06-15 16:00:17
Also in:
linux-block, linux-fsdevel
Subsystem:
aio, filesystems (vfs and infrastructure), the rest · Maintainers:
Benjamin LaHaise, Alexander Viro, Christian Brauner, Linus Torvalds
From: Goldwyn Rodrigues <redacted> 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. FMODE_AIO_NOWAIT is a flag which identifies the file opened is capable of returning -EAGAIN if the AIO call will block. This must be set by supporting filesystems in the ->open() call. Filesystems xfs, btrfs and ext4 would be supported in the following patches. Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Goldwyn Rodrigues <redacted> --- fs/aio.c | 6 ++++++ include/linux/fs.h | 11 ++++++++++- include/uapi/linux/fs.h | 1 + 3 files changed, 17 insertions(+), 1 deletion(-)
diff --git a/fs/aio.c b/fs/aio.c
index 020fa0045e3c..34027b67e2f4 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/include/linux/fs.h b/include/linux/fs.h
index dc0ab585cd56..017aca01c35e 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h@@ -142,6 +142,9 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset, /* File was opened by fanotify and shouldn't generate fanotify events */ #define FMODE_NONOTIFY ((__force fmode_t)0x4000000) +/* File is capable of returning -EAGAIN if AIO will block */ +#define FMODE_AIO_NOWAIT ((__force fmode_t)0x8000000) + /* * Flag for rw_copy_check_uvector and compat_rw_copy_check_uvector * that indicates that they should check the contents of the iovec are
@@ -268,6 +271,7 @@ 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;
@@ -3060,9 +3064,14 @@ 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_NOWAIT) { + if (!(ki->ki_filp->f_mode & FMODE_AIO_NOWAIT)) + return -EOPNOTSUPP; + ki->ki_flags |= IOCB_NOWAIT; + } if (flags & RWF_HIPRI) ki->ki_flags |= IOCB_HIPRI; if (flags & RWF_DSYNC)
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 */
--
2.12.0