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vfs: add the RWF_HIPRI flag for preadv2/pwritev2

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This adds a flag that tells the file system that this is a high priority
request for which it's worth to poll the hardware.  The flag is purely
advisory and can be ignored if not supported.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Stephen Bates <stephen.bates@pmcs.com>
Tested-by: Stephen Bates <stephen.bates@pmcs.com>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Christoph Hellwig 2016-03-03 16:04:01 +01:00 committed by Al Viro
parent 4babf2c5ef
commit 97be7ebe53
3 changed files with 8 additions and 2 deletions
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6
fs/read_write.c
View File

@ -697,10 +697,12 @@ static ssize_t do_iter_readv_writev(struct file *filp, struct iov_iter *iter,
struct kiocb kiocb;
ssize_t ret;
if (flags)
if (flags & ~RWF_HIPRI)
return -EOPNOTSUPP;
init_sync_kiocb(&kiocb, filp);
if (flags & RWF_HIPRI)
kiocb.ki_flags |= IOCB_HIPRI;
kiocb.ki_pos = *ppos;
ret = fn(&kiocb, iter);
@ -715,7 +717,7 @@ static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter,
{
ssize_t ret = 0;
if (flags)
if (flags & ~RWF_HIPRI)
return -EOPNOTSUPP;
while (iov_iter_count(iter)) {

1
include/linux/fs.h
View File

@ -320,6 +320,7 @@ struct writeback_control;
#define IOCB_EVENTFD (1 << 0)
#define IOCB_APPEND (1 << 1)
#define IOCB_DIRECT (1 << 2)
#define IOCB_HIPRI (1 << 3)
struct kiocb {
struct file *ki_filp;

3
include/uapi/linux/fs.h
View File

@ -305,4 +305,7 @@ struct fsxattr {
#define SYNC_FILE_RANGE_WRITE 2
#define SYNC_FILE_RANGE_WAIT_AFTER 4
/* flags for preadv2/pwritev2: */
#define RWF_HIPRI 0x00000001 /* high priority request, poll if possible */
#endif /* _UAPI_LINUX_FS_H */