On 8/23/24 17:27, Mark Harmstone wrote:
Adds an io_uring interface for asynchronous encoded reads, using the
same interface as for the ioctl. To use this you would use an SQE opcode
of IORING_OP_URING_CMD, the cmd_op would be BTRFS_IOC_ENCODED_READ, and
addr would point to the userspace address of the
btrfs_ioctl_encoded_io_args struct. As with the ioctl, you need to have
CAP_SYS_ADMIN for this to work.
Signed-off-by: Mark Harmstone <maharmstone@xxxxxx>
---
...
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 1bd4c74e8c51..e4458168c340 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -34,6 +34,7 @@
#include <linux/iomap.h>
#include <asm/unaligned.h>
#include <linux/fsverity.h>
+#include <linux/io_uring/cmd.h>
#include "misc.h"
#include "ctree.h"
#include "disk-io.h"
@@ -9078,7 +9079,7 @@ static ssize_t btrfs_encoded_read_inline(
return ret;
}
-static void btrfs_encoded_read_endio(struct btrfs_bio *bbio)
+static void btrfs_encoded_read_ioctl_endio(struct btrfs_bio *bbio)
{
struct btrfs_encoded_read_private *priv = bbio->private;
@@ -9098,6 +9099,47 @@ static void btrfs_encoded_read_endio(struct btrfs_bio *bbio)
bio_put(&bbio->bio);
}
+static inline struct btrfs_encoded_read_private *btrfs_uring_encoded_read_pdu(
+ struct io_uring_cmd *cmd)
+{
+ return *(struct btrfs_encoded_read_private **)cmd->pdu;
+}
+static void btrfs_finish_uring_encoded_read(struct io_uring_cmd *cmd,
+ unsigned int issue_flags)
+{
+ struct btrfs_encoded_read_private *priv;
+ ssize_t ret;
+
+ priv = btrfs_uring_encoded_read_pdu(cmd);
+ ret = btrfs_encoded_read_finish(priv, -EIOCBQUEUED);
tw callback -> btrfs_encoded_read_finish() -> copy_to_user()
That's usually fine except cases when the task and/or io_uring are dying
and the callback executes not from a user task context. Same problem as
with fuse, we can pass a flag from io_uring into the callback telling
btrfs that it should terminate the request and not rely on mm or any
other task related pieces.
+
+ io_uring_cmd_done(priv->cmd, ret, 0, priv->issue_flags);
+
+ kfree(priv);
+}
+
...
--
Pavel Begunkov
