Commit b9f958d4 authored by Jens Axboe's avatar Jens Axboe Committed by Andrew Morton
Browse files

fs: add RWF_DONTCACHE iocb and FOP_DONTCACHE file_operations flag 

If a file system supports uncached buffered IO, it may set FOP_DONTCACHE
and enable support for RWF_DONTCACHE.  If RWF_DONTCACHE is attempted
without the file system supporting it, it'll get errored with -EOPNOTSUPP.

Link: https://lkml.kernel.org/r/20241220154831.1086649-8-axboe@kernel.dk


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Chris Mason <clm@meta.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 4a9e2315

include/linux/fs.h

+13 −1
Original line number Diff line number Diff line
@@ -322,6 +322,7 @@ struct readahead_control; 
#define IOCB_NOWAIT		(__force int) RWF_NOWAIT

#define IOCB_APPEND		(__force int) RWF_APPEND

#define IOCB_ATOMIC		(__force int) RWF_ATOMIC

#define IOCB_DONTCACHE		(__force int) RWF_DONTCACHE



/* non-RWF related bits - start at 16 */

#define IOCB_EVENTFD		(1 << 16)
@@ -357,6 +358,7 @@ struct readahead_control; 
	{ IOCB_NOWAIT,		"NOWAIT" }, \

	{ IOCB_APPEND,		"APPEND" }, \

	{ IOCB_ATOMIC,		"ATOMIC" }, \

	{ IOCB_DONTCACHE,	"DONTCACHE" }, \

	{ IOCB_EVENTFD,		"EVENTFD"}, \

	{ IOCB_DIRECT,		"DIRECT" }, \

	{ IOCB_WRITE,		"WRITE" }, \
@@ -2127,6 +2129,8 @@ struct file_operations { 
#define FOP_UNSIGNED_OFFSET	((__force fop_flags_t)(1 << 5))

/* Supports asynchronous lock callbacks */

#define FOP_ASYNC_LOCK		((__force fop_flags_t)(1 << 6))

/* File system supports uncached read/write buffered IO */

#define FOP_DONTCACHE		((__force fop_flags_t)(1 << 7))



/* Wrap a directory iterator that needs exclusive inode access */

int wrap_directory_iterator(struct file *, struct dir_context *,
@@ -3614,6 +3618,14 @@ static inline int kiocb_set_rw_flags(struct kiocb *ki, rwf_t flags, 
		if (!(ki->ki_filp->f_mode & FMODE_CAN_ATOMIC_WRITE))

			return -EOPNOTSUPP;

	}

	if (flags & RWF_DONTCACHE) {

		/* file system must support it */

		if (!(ki->ki_filp->f_op->fop_flags & FOP_DONTCACHE))

			return -EOPNOTSUPP;

		/* DAX mappings not supported */

		if (IS_DAX(ki->ki_filp->f_mapping->host))

			return -EOPNOTSUPP;

	}

	kiocb_flags |= (__force int) (flags & RWF_SUPPORTED);

	if (flags & RWF_SYNC)

		kiocb_flags |= IOCB_DSYNC;

include/uapi/linux/fs.h

+5 −1
Original line number Diff line number Diff line
@@ -332,9 +332,13 @@ typedef int __bitwise __kernel_rwf_t; 
/* Atomic Write */

#define RWF_ATOMIC	((__force __kernel_rwf_t)0x00000040)



/* buffered IO that drops the cache after reading or writing data */

#define RWF_DONTCACHE	((__force __kernel_rwf_t)0x00000080)



/* mask of flags supported by the kernel */

#define RWF_SUPPORTED	(RWF_HIPRI | RWF_DSYNC | RWF_SYNC | RWF_NOWAIT |\

			 RWF_APPEND | RWF_NOAPPEND | RWF_ATOMIC)

			 RWF_APPEND | RWF_NOAPPEND | RWF_ATOMIC |\

			 RWF_DONTCACHE)



#define PROCFS_IOCTL_MAGIC 'f'