Re: [PATCH 4/7] vfs: add the RWF_HIPRI flag for preadv2/pwritev2
From: Jeff Moyer <hidden>
Date: 2016-02-26 21:56:05
Christoph Hellwig [off-list ref] writes:
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.
I'm not in love with the HIGHPRI name, but I don't have a better one in mind. So... Acked-by: Jeff Moyer <redacted>
quoted hunk
Signed-off-by: Christoph Hellwig <redacted> --- fs/read_write.c | 6 ++++-- include/linux/fs.h | 1 + include/uapi/linux/fs.h | 3 +++ 3 files changed, 8 insertions(+), 2 deletions(-)diff --git a/fs/read_write.c b/fs/read_write.c index 38b9afa..3b3fb22 100644 --- a/fs/read_write.c +++ b/fs/read_write.c@@ -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)) {diff --git a/include/linux/fs.h b/include/linux/fs.h index 875277a..a1f731c 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h@@ -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;diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h index 149bec8..d246339 100644 --- a/include/uapi/linux/fs.h +++ b/include/uapi/linux/fs.h@@ -304,4 +304,7 @@ 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 */