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@xxxxxx>
---
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 */
--
2.1.4
--
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