fs: add RWF_APPEND (e1fc742e) · Commits · 戴 / test

This is the per-I/O equivalent of O_APPEND to support atomic append operations on any open file. If a file is opened with O_APPEND, pwrite() ignores the offset and always appends data to the end of the file. RWF_APPEND enables atomic append and pwrite() with offset on a single file descriptor. Signed-off-by:

Jürg Billeter <j@bitron.ch> Signed-off-by:

Al Viro <viro@zeniv.linux.org.uk>

include/linux/fs.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -3224,6 +3224,8 @@ static inline int kiocb_set_rw_flags(struct kiocb *ki, rwf_t flags)
		ki->ki_flags \|= IOCB_DSYNC;
		if (flags & RWF_SYNC)
		ki->ki_flags \|= (IOCB_DSYNC \| IOCB_SYNC);
		if (flags & RWF_APPEND)
		ki->ki_flags \|= IOCB_APPEND;
		return 0;
		}

include/uapi/linux/fs.h

+5 −1

Original line number	Diff line number	Diff line
		@@ -377,7 +377,11 @@ typedef int __bitwise __kernel_rwf_t;
		/* per-IO, return -EAGAIN if operation would block */
		#define RWF_NOWAIT ((__force __kernel_rwf_t)0x00000008)

		/* per-IO O_APPEND */
		#define RWF_APPEND ((__force __kernel_rwf_t)0x00000010)

		/* mask of flags supported by the kernel */
		#define RWF_SUPPORTED (RWF_HIPRI \| RWF_DSYNC \| RWF_SYNC \| RWF_NOWAIT)
		#define RWF_SUPPORTED (RWF_HIPRI \| RWF_DSYNC \| RWF_SYNC \| RWF_NOWAIT \|\
		RWF_APPEND)

		#endif /* _UAPI_LINUX_FS_H */

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