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SubjectRe: [PATCH v3 12/20] ceph: Make ceph_init_request() check caps on readahead
Date
Jeff Layton <jlayton@redhat.com> wrote:

> > +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;
> > + int ret = 0;
> > +
> > + 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)
> > + return 0;
> > + }
> > +
> > + if (rreq->origin != NETFS_READAHEAD)
> > + return 0;
> > +
>
> ^^^
> I think you should move this check above the if (file) block above it.
> We don't need to anything at all if we're not in readahead.

How about the attached, then?

David
---
commit 7082946186fc26016b15bc9039bd6d92ae732ef3
Author: David Howells <dhowells@redhat.com>
Date: Wed Mar 9 21:45:22 2022 +0000

ceph: Make ceph_init_request() check caps on readahead

Move the caps check from ceph_readahead() to ceph_init_request(),
conditional on the origin being NETFS_READAHEAD so that in a future patch,
ceph can point its ->readahead() vector directly at netfs_readahead().

Changes
=======
ver #4)
- Move the check for NETFS_READAHEAD up in ceph_init_request()[2].

ver #3)
- Split from the patch to add a netfs inode context[1].
- Need to store the caps got in rreq->netfs_priv for later freeing.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: ceph-devel@vger.kernel.org
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/8af0d47f17d89c06bbf602496dd845f2b0bf25b3.camel@kernel.org/ [1]
Link: https://lore.kernel.org/r/dd054c962818716e718bd9b446ee5322ca097675.camel@redhat.com/ [2]

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 9189257476f8..4aeccafa5dda 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -354,6 +354,45 @@ static void ceph_netfs_issue_read(struct netfs_io_subrequest *subreq)
dout("%s: result %d\n", __func__, err);
}

+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;
+ int ret = 0;
+
+ if (rreq->origin != NETFS_READAHEAD)
+ return 0;
+
+ 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)
+ return 0;
+ }
+
+ /*
+ * readahead callers do not necessarily hold Fcb caps
+ * (e.g. fadvise, madvise).
+ */
+ 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;
+ }
+
+ if (!(got & want)) {
+ dout("start_read %p, no cache cap\n", inode);
+ return -EACCES;
+ }
+ if (ret == 0)
+ return -EACCES;
+
+ rreq->netfs_priv = (void *)(uintptr_t)got;
+ return 0;
+}
+
static void ceph_readahead_cleanup(struct address_space *mapping, void *priv)
{
struct inode *inode = mapping->host;
@@ -365,7 +404,7 @@ static void ceph_readahead_cleanup(struct address_space *mapping, void *priv)
}

static const struct netfs_request_ops ceph_netfs_read_ops = {
- .is_cache_enabled = ceph_is_cache_enabled,
+ .init_request = ceph_init_request,
.begin_cache_operation = ceph_begin_cache_operation,
.issue_read = ceph_netfs_issue_read,
.expand_readahead = ceph_netfs_expand_readahead,
@@ -393,33 +432,7 @@ static int ceph_readpage(struct file *file, struct page *subpage)

static void ceph_readahead(struct readahead_control *ractl)
{
- struct inode *inode = file_inode(ractl->file);
- struct ceph_file_info *fi = ractl->file->private_data;
- struct ceph_rw_context *rw_ctx;
- int got = 0;
- int ret = 0;
-
- if (ceph_inode(inode)->i_inline_version != CEPH_INLINE_NONE)
- return;
-
- rw_ctx = ceph_find_rw_context(fi);
- if (!rw_ctx) {
- /*
- * readahead callers do not necessarily hold Fcb caps
- * (e.g. fadvise, madvise).
- */
- int want = CEPH_CAP_FILE_CACHE;
-
- 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);
- else if (!(got & want))
- dout("start_read %p, no cache cap\n", inode);
-
- if (ret <= 0)
- return;
- }
- netfs_readahead(ractl, &ceph_netfs_read_ops, (void *)(uintptr_t)got);
+ netfs_readahead(ractl, &ceph_netfs_read_ops, NULL);
}

#ifdef CONFIG_CEPH_FSCACHE
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