This fcntl can be used to query I/O parameters for the given file
descriptor. Initially it is used for the I/O alignment and atomic
write parameters.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
fs/fcntl.c | 18 ++++++++++++++++++
include/linux/fs.h | 1 +
include/uapi/linux/fcntl.h | 16 ++++++++++++++++
3 files changed, 35 insertions(+)
diff --git a/fs/fcntl.c b/fs/fcntl.c
index ca5d228be7ea..248fb4cc66a6 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -241,6 +241,21 @@ static int f_getowner_uids(struct file *filp, unsigned long arg)
}
#endif
+static int fcntl_ioinfo(struct file *file, void __user *argp)
+{
+ struct fcntl_ioinfo fio = { 0, };
+
+ if (file->f_op->ioinfo) {
+ int ret = file->f_op->ioinfo(file, &fio);
+ if (ret)
+ return ret;
+ }
+
+ if (copy_to_user(argp, &fio, sizeof(fio)))
+ return -EFAULT;
+ return 0;
+}
+
static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
struct file *filp)
{
@@ -335,6 +350,9 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
case F_GET_SEALS:
err = shmem_fcntl(filp, cmd, arg);
break;
+ case F_IOINFO:
+ err = fcntl_ioinfo(filp, (void __user *)arg);
+ break;
default:
break;
}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 2ba074328894..33b08a8c2bc3 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1680,6 +1680,7 @@ struct file_operations {
u64);
ssize_t (*dedupe_file_range)(struct file *, u64, u64, struct file *,
u64);
+ int (*ioinfo)(struct file *, struct fcntl_ioinfo *);
};
struct inode_operations {
diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h
index beed138bd359..6b0aaba7c623 100644
--- a/include/uapi/linux/fcntl.h
+++ b/include/uapi/linux/fcntl.h
@@ -42,6 +42,22 @@
#define F_SEAL_WRITE 0x0008 /* prevent writes */
/* (1U << 31) is reserved for signed error codes */
+
+#define F_IOINFO (F_LINUX_SPECIFIC_BASE + 11)
+
+struct fcntl_ioinfo {
+ __u16 fio_flags; /* FIO_FL_* */
+ __u16 fio_alignment; /* required I/O alignment on disk */
+ __u32 __reserved1; /* must be zero */
+ __u64 fio_max_atomic; /* max size for atomic writes */
+ __u64 __reserved2[14];/* must be zero */
+};
+
+/* supports atomic writes using O_(D)SYNC */
+#define FIO_FL_ATOMIC_OSYNC (1 << 0)
+/* supports atomic writes committed using fsync/fdatasync/msync */
+#define FIO_FL_ATOMIC_FSYNC (1 << 1)
+
/*
* Types of directory notifications that may be requested.
*/
--
2.11.0
--
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