Enable zone-append using existing O_APPEND and RWF_APPEND.
Zone-append is similar to appending writes, but requires written-location
to be returned, in order to be effective.
Returning completion-result requires bit of additional processing in
common path. Also, we guarantee that zone-append does not cause a short
write, which is not the case with regular appending-write.
Therefore make the feature opt-in by introducing new FMODE_ZONE_APPEND
mode (kernel-only) and IOCB_ZONE_APPEND flag.
When a file is opened, it can opt in for zone-append by setting
FMODE_ZONE_APPEND.
If file has opted in, and receives write that meets file-append
criteria (RWF_APPEND write or O_APPEND open), set IOCB_ZONE_APPEND in
kiocb->ki_flag, apart from existing IOCB_APPEND. IOCB_ZONE_APPEND is
meant to isolate the code that returns written-location with appending
write.
Signed-off-by: Kanchan Joshi <joshi.k@xxxxxxxxxxx>
Signed-off-by: Selvakumar S <selvakuma.s1@xxxxxxxxxxx>
Signed-off-by: Nitesh Shetty <nj.shetty@xxxxxxxxxxx>
Signed-off-by: Javier Gonzalez <javier.gonz@xxxxxxxxxxx>
---
include/linux/fs.h | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 6c4ab4d..ef13df4 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -175,6 +175,9 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
/* File does not contribute to nr_files count */
#define FMODE_NOACCOUNT ((__force fmode_t)0x20000000)
+/* File can support zone-append */
+#define FMODE_ZONE_APPEND ((__force fmode_t)0x40000000)
+
/*
* Flag for rw_copy_check_uvector and compat_rw_copy_check_uvector
* that indicates that they should check the contents of the iovec are
@@ -315,6 +318,7 @@ enum rw_hint {
#define IOCB_SYNC (1 << 5)
#define IOCB_WRITE (1 << 6)
#define IOCB_NOWAIT (1 << 7)
+#define IOCB_ZONE_APPEND (1 << 8)
struct kiocb {
struct file *ki_filp;
@@ -3427,8 +3431,11 @@ static inline bool vma_is_fsdax(struct vm_area_struct *vma)
static inline int iocb_flags(struct file *file)
{
int res = 0;
- if (file->f_flags & O_APPEND)
+ if (file->f_flags & O_APPEND) {
res |= IOCB_APPEND;
+ if (file->f_mode & FMODE_ZONE_APPEND)
+ res |= IOCB_ZONE_APPEND;
+ }
if (file->f_flags & O_DIRECT)
res |= IOCB_DIRECT;
if ((file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host))
@@ -3454,8 +3461,11 @@ static inline int kiocb_set_rw_flags(struct kiocb *ki, rwf_t flags)
ki->ki_flags |= IOCB_DSYNC;
if (flags & RWF_SYNC)
ki->ki_flags |= (IOCB_DSYNC | IOCB_SYNC);
- if (flags & RWF_APPEND)
+ if (flags & RWF_APPEND) {
ki->ki_flags |= IOCB_APPEND;
+ if (ki->ki_filp->f_mode & FMODE_ZONE_APPEND)
+ ki->ki_flags |= IOCB_ZONE_APPEND;
+ }
return 0;
}
--
2.7.4
