Re: [PATCH v5 1/2] ceph: add a dedicated private data for netfs rreq

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On 5/12/23 22:13, 胡玮文 wrote:
On Thu, May 11, 2023 at 11:03:34AM +0800, xiubli@xxxxxxxxxx wrote:
From: Xiubo Li <xiubli@xxxxxxxxxx>

We need to save the 'f_ra.ra_pages' to expand the readahead window
later.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: 49870056005c ("ceph: convert ceph_readpages to ceph_readahead")
URL: https://lore.kernel.org/ceph-devel/20230504082510.247-1-sehuww@xxxxxxxxxxxxxxxx
URL: https://www.spinics.net/lists/ceph-users/msg76183.html
Cc: Hu Weiwen <sehuww@xxxxxxxxxxxxxxxx>
Signed-off-by: Xiubo Li <xiubli@xxxxxxxxxx>
---
  fs/ceph/addr.c  | 43 ++++++++++++++++++++++++++++++++-----------
  fs/ceph/super.h | 13 +++++++++++++
  2 files changed, 45 insertions(+), 11 deletions(-)

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 3b20873733af..db55fce13324 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -404,18 +404,27 @@ static int ceph_init_request(struct netfs_io_request *rreq, struct file *file)
  {
  	struct inode *inode = rreq->inode;
  	int got = 0, want = CEPH_CAP_FILE_CACHE;
+	struct ceph_netfs_request_data *priv;
  	int ret = 0;
if (rreq->origin != NETFS_READAHEAD)
  		return 0;
+ priv = kzalloc(sizeof(*priv), GFP_NOFS);
+	if (!priv)
+		return -ENOMEM;
+
  	if (file) {
  		struct ceph_rw_context *rw_ctx;
  		struct ceph_file_info *fi = file->private_data;
rw_ctx = ceph_find_rw_context(fi);
-		if (rw_ctx)
+		if (rw_ctx) {
+			kfree(priv);
  			return 0;
This is not working. When reaching here by read() system call, we always
have non-null rw_ctx.  (As I read the code and also verified with gdb)
ceph_add_rw_context() is invoked in ceph_read_iter().

This should work:

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index e1bf90059112..d3e37e01c3d0 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -444,13 +444,14 @@ static int ceph_init_request(struct netfs_io_request *rreq, struct file *file)
                struct ceph_rw_context *rw_ctx;
                struct ceph_file_info *fi = file->private_data;

+               priv->file_ra_pages = file->f_ra.ra_pages;
+               priv->file_ra_disabled = file->f_mode & FMODE_RANDOM;
+
                rw_ctx = ceph_find_rw_context(fi);
                if (rw_ctx) {
-                       kfree(priv);
+                       rreq->netfs_priv = priv;
                        return 0;
                }
-               priv->file_ra_pages = file->f_ra.ra_pages;
-               priv->file_ra_disabled = !!(file->f_mode & FMODE_RANDOM);
        }

        /*

Thanks

- Xiubo

+		}
+		priv->file_ra_pages = file->f_ra.ra_pages;
+		priv->file_ra_disabled = !!(file->f_mode & FMODE_RANDOM);
'!!' is not needed. From coding-style.rst: "When using bool types the
!! construction is not needed, which eliminates a class of bugs".

Thanks
Hu Weiwen

  	}
/*
@@ -425,27 +434,39 @@ static int ceph_init_request(struct netfs_io_request *rreq, struct file *file)
  	ret = ceph_try_get_caps(inode, CEPH_CAP_FILE_RD, want, true, &got);
  	if (ret < 0) {
  		dout("start_read %p, error getting cap\n", inode);
-		return ret;
+		goto out;
  	}
if (!(got & want)) {
  		dout("start_read %p, no cache cap\n", inode);
-		return -EACCES;
+		ret = -EACCES;
+		goto out;
+	}
+	if (ret == 0) {
+		ret = -EACCES;
+		goto out;
  	}
-	if (ret == 0)
-		return -EACCES;
- rreq->netfs_priv = (void *)(uintptr_t)got;
-	return 0;
+	priv->caps = got;
+	rreq->netfs_priv = priv;
+
+out:
+	if (ret)
+		kfree(priv);
+
+	return ret;
  }
static void ceph_netfs_free_request(struct netfs_io_request *rreq)
  {
-	struct ceph_inode_info *ci = ceph_inode(rreq->inode);
-	int got = (uintptr_t)rreq->netfs_priv;
+	struct ceph_netfs_request_data *priv = rreq->netfs_priv;
+
+	if (!priv)
+		return;
- if (got)
-		ceph_put_cap_refs(ci, got);
+	ceph_put_cap_refs(ceph_inode(rreq->inode), priv->caps);
+	kfree(priv);
+	rreq->netfs_priv = NULL;
  }
const struct netfs_request_ops ceph_netfs_ops = {
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index a226d36b3ecb..1233f53f6e0b 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -470,6 +470,19 @@ struct ceph_inode_info {
  #endif
  };
+struct ceph_netfs_request_data {
+	int caps;
+
+	/*
+	 * Maximum size of a file readahead request.
+	 * The posix_fadvise could update the bdi's default ra_pages.
+	 */
+	unsigned int file_ra_pages;
+
+	/* Set it if posix_fadvise disables file readahead entirely */
+	bool file_ra_disabled;
+};
+
  static inline struct ceph_inode_info *
  ceph_inode(const struct inode *inode)
  {
--
2.40.0





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