Add four flags for the pwritev2(2) system call, allowing an application
to give the kernel a hint about what on-media life times can be
expected from a given write.
The intent is for these values to be relative to each other, no
absolute meaning should be attached to these flag names.
Define IOCB flags to carry this information over, and finally
transform them into the block defined stream values.
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
fs/read_write.c | 9 ++++++++-
include/linux/fs.h | 12 ++++++++++++
include/uapi/linux/fs.h | 10 ++++++++++
3 files changed, 30 insertions(+), 1 deletion(-)
diff --git a/fs/read_write.c b/fs/read_write.c
index 47c1d4484df9..a9b0c3125e0f 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -678,7 +678,7 @@ static ssize_t do_iter_readv_writev(struct file *filp, struct iov_iter *iter,
struct kiocb kiocb;
ssize_t ret;
- if (flags & ~(RWF_HIPRI | RWF_DSYNC | RWF_SYNC))
+ if (flags & ~(RWF_HIPRI | RWF_DSYNC | RWF_SYNC | RWF_WRITE_LIFE_MASK))
return -EOPNOTSUPP;
init_sync_kiocb(&kiocb, filp);
@@ -688,6 +688,13 @@ static ssize_t do_iter_readv_writev(struct file *filp, struct iov_iter *iter,
kiocb.ki_flags |= IOCB_DSYNC;
if (flags & RWF_SYNC)
kiocb.ki_flags |= (IOCB_DSYNC | IOCB_SYNC);
+ if (flags & RWF_WRITE_LIFE_MASK) {
+ struct inode *inode = file_inode(filp);
+
+ inode->i_stream = (flags & RWF_WRITE_LIFE_MASK) >>
+ RWF_WRITE_LIFE_SHIFT;
+ kiocb.ki_flags |= inode->i_stream << IOCB_WRITE_LIFE_SHIFT;
+ }
kiocb.ki_pos = *ppos;
if (type == READ)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 771e172d23d7..751a1046e87b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -269,6 +269,12 @@ struct writeback_control;
#define IOCB_SYNC (1 << 5)
#define IOCB_WRITE (1 << 6)
+/*
+ * Steal 4-bits for stream information, this allows 16 valid streams
+ */
+#define IOCB_WRITE_LIFE_SHIFT 7
+#define IOCB_WRITE_LIFE_MASK (BIT(7) | BIT(8) | BIT(9) | BIT(10))
+
struct kiocb {
struct file *ki_filp;
loff_t ki_pos;
@@ -292,6 +298,12 @@ static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp)
};
}
+static inline int iocb_streamid(const struct kiocb *iocb)
+{
+ return (iocb->ki_flags & IOCB_WRITE_LIFE_MASK) >>
+ IOCB_WRITE_LIFE_SHIFT;
+}
+
/*
* "descriptor" for what we're up to with a read.
* This allows us to use the same read code yet
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 24e61a54feaa..8a7e6f26f6f5 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -361,4 +361,14 @@ struct fscrypt_key {
#define RWF_DSYNC 0x00000002 /* per-IO O_DSYNC */
#define RWF_SYNC 0x00000004 /* per-IO O_SYNC */
+/*
+ * Data life time write flags, steal 4 bits for that
+ */
+#define RWF_WRITE_LIFE_SHIFT 3
+#define RWF_WRITE_LIFE_MASK 0x000000f0 /* 4 bits of stream ID */
+#define RWF_WRITE_LIFE_SHORT (1 << RWF_WRITE_LIFE_SHIFT)
+#define RWF_WRITE_LIFE_MEDIUM (2 << RWF_WRITE_LIFE_SHIFT)
+#define RWF_WRITE_LIFE_LONG (3 << RWF_WRITE_LIFE_SHIFT)
+#define RWF_WRITE_LIFE_EXTREME (4 << RWF_WRITE_LIFE_SHIFT)
+
#endif /* _UAPI_LINUX_FS_H */
--
2.7.4
