[PATCH v8 06/19] block, fs: Propagate write hints to the block device inode

Bart Van Assche
2023-12-19T00:08:42Z

Write hints applied with F_SET_RW_HINT on a block device affect the
shmem inode only. Propagate these hints to the block device inode
because that is the inode used when writing back dirty pages.

Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
block/fops.c | 11 +++++++++++
fs/fcntl.c | 4 ++++
include/linux/fs.h | 1 +
3 files changed, 16 insertions(+)

diff --git a/block/fops.c b/block/fops.c
index 787ce52bc2c6..138b388b5cb1 100644
--- a/block/fops.c
+++ b/block/fops.c
@@ -620,6 +620,16 @@ static int blkdev_release(struct inode *inode, struct file *filp)
return 0;
}

+static void blkdev_apply_whint(struct file *file, enum rw_hint hint)
+{
+ struct bdev_handle *handle = file->private_data;
+ struct inode *bd_inode = handle->bdev->bd_inode;
+
+ inode_lock(bd_inode);
+ bd_inode->i_write_hint = hint;
+ inode_unlock(bd_inode);
+}
+
static ssize_t
blkdev_direct_write(struct kiocb *iocb, struct iov_iter *from)
{
@@ -854,6 +864,7 @@ const struct file_operations def_blk_fops = {
.splice_read = filemap_splice_read,
.splice_write = iter_file_splice_write,
.fallocate = blkdev_fallocate,
+ .apply_whint = blkdev_apply_whint,
};

static __init int blkdev_init(void)
diff --git a/fs/fcntl.c b/fs/fcntl.c
index fc73c5fae43c..18407bf5bb9b 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -306,6 +306,7 @@ static long fcntl_get_rw_hint(struct file *file, unsigned int cmd,
static long fcntl_set_rw_hint(struct file *file, unsigned int cmd,
unsigned long arg)
{
+ void (*apply_whint)(struct file *, enum rw_hint);
struct inode *inode = file_inode(file);
u64 __user *argp = (u64 __user *)arg;
u64 hint;
@@ -317,6 +318,9 @@ static long fcntl_set_rw_hint(struct file *file, unsigned int cmd,

inode_lock(inode);
inode->i_write_hint = hint;
+ apply_whint = inode->i_fop->apply_whint;
+ if (apply_whint)
+ apply_whint(file, hint);
inode_unlock(inode);

return 0;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index a08014b68d6e..293017ea2466 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1944,6 +1944,7 @@ struct file_operations {
int (*uring_cmd)(struct io_uring_cmd *ioucmd, unsigned int issue_flags);
int (*uring_cmd_iopoll)(struct io_uring_cmd *, struct io_comp_batch *,
unsigned int poll_flags);
+ void (*apply_whint)(struct file *, enum rw_hint hint);
} __randomize_layout;

/* Wrap a directory iterator that needs exclusive inode access */