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Message-ID: <52e0e743e006801cb4bcf8322e80704964cf6e25.1756635044.git.repk@triplefau.lt>
Date: Sun, 31 Aug 2025 21:03:41 +0200
From: Remi Pommarel <repk@...plefau.lt>
To: v9fs@...ts.linux.dev
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
Eric Van Hensbergen <ericvh@...nel.org>,
Latchesar Ionkov <lucho@...kov.net>,
Dominique Martinet <asmadeus@...ewreck.org>,
Christian Schoenebeck <linux_oss@...debyte.com>,
Remi Pommarel <repk@...plefau.lt>
Subject: [RFC PATCH 3/5] 9p: Enable symlink caching in page cache
Currently, when cache=loose is enabled, file reads are cached in the
page cache, but symlink reads are not. This patch allows the results
of p9_client_readlink() to be stored in the page cache, eliminating
the need for repeated 9P transactions on subsequent symlink accesses.
This change improves performance for workloads that involve frequent
symlink resolution.
Signed-off-by: Remi Pommarel <repk@...plefau.lt>
---
fs/9p/v9fs.h | 1 +
fs/9p/vfs_inode.c | 7 +++-
fs/9p/vfs_inode_dotl.c | 94 +++++++++++++++++++++++++++++++++++++-----
3 files changed, 90 insertions(+), 12 deletions(-)
diff --git a/fs/9p/v9fs.h b/fs/9p/v9fs.h
index 8c5fa0f7ba71..f48a85b610e3 100644
--- a/fs/9p/v9fs.h
+++ b/fs/9p/v9fs.h
@@ -186,6 +186,7 @@ extern struct inode *v9fs_inode_from_fid(struct v9fs_session_info *v9ses,
struct super_block *sb, int new);
extern const struct inode_operations v9fs_dir_inode_operations_dotl;
extern const struct inode_operations v9fs_file_inode_operations_dotl;
+extern const struct address_space_operations v9fs_symlink_aops_dotl;
extern const struct inode_operations v9fs_symlink_inode_operations_dotl;
extern const struct netfs_request_ops v9fs_req_ops;
extern struct inode *v9fs_inode_from_fid_dotl(struct v9fs_session_info *v9ses,
diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 89eeb2b3ba43..362e39b3e7eb 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -302,10 +302,13 @@ int v9fs_init_inode(struct v9fs_session_info *v9ses,
goto error;
}
- if (v9fs_proto_dotl(v9ses))
+ if (v9fs_proto_dotl(v9ses)) {
inode->i_op = &v9fs_symlink_inode_operations_dotl;
- else
+ inode->i_mapping->a_ops = &v9fs_symlink_aops_dotl;
+ inode_nohighmem(inode);
+ } else {
inode->i_op = &v9fs_symlink_inode_operations;
+ }
break;
case S_IFDIR:
diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c
index 5b5fda617b80..2e2119be1d49 100644
--- a/fs/9p/vfs_inode_dotl.c
+++ b/fs/9p/vfs_inode_dotl.c
@@ -126,8 +126,10 @@ static struct inode *v9fs_qid_iget_dotl(struct super_block *sb,
goto error;
v9fs_stat2inode_dotl(st, inode, 0);
- v9fs_set_netfs_context(inode);
- v9fs_cache_inode_get_cookie(inode);
+ if (inode->i_mapping->a_ops == &v9fs_addr_operations) {
+ v9fs_set_netfs_context(inode);
+ v9fs_cache_inode_get_cookie(inode);
+ }
retval = v9fs_get_acl(inode, fid);
if (retval)
goto error;
@@ -858,24 +860,23 @@ v9fs_vfs_mknod_dotl(struct mnt_idmap *idmap, struct inode *dir,
}
/**
- * v9fs_vfs_get_link_dotl - follow a symlink path
+ * v9fs_vfs_get_link_nocache_dotl - Resolve a symlink directly.
+ *
+ * To be used when symlink caching is not enabled.
+ *
* @dentry: dentry for symlink
* @inode: inode for symlink
* @done: destructor for return value
*/
-
static const char *
-v9fs_vfs_get_link_dotl(struct dentry *dentry,
- struct inode *inode,
- struct delayed_call *done)
+v9fs_vfs_get_link_nocache_dotl(struct dentry *dentry,
+ struct inode *inode,
+ struct delayed_call *done)
{
struct p9_fid *fid;
char *target;
int retval;
- if (!dentry)
- return ERR_PTR(-ECHILD);
-
p9_debug(P9_DEBUG_VFS, "%pd\n", dentry);
fid = v9fs_fid_lookup(dentry);
@@ -889,6 +890,75 @@ v9fs_vfs_get_link_dotl(struct dentry *dentry,
return target;
}
+/**
+ * v9fs_symlink_read_folio_dotl - Fetch a symlink path and store it in buffer
+ * cache.
+ * @file: file associated to symlink (NULL)
+ * @folio: folio where to store the symlink resolve result
+ */
+static int v9fs_symlink_read_folio_dotl(struct file *file,
+ struct folio *folio)
+{
+ struct inode *inode = folio->mapping->host;
+ struct dentry *dentry;
+ struct p9_fid *fid;
+ char *target;
+ size_t len;
+ int ret = -EIO;
+
+ /* Does not expect symlink inode to have a fid as it as not been
+ * opened>
+ */
+ dentry = d_find_alias(inode);
+ if (!dentry)
+ goto out;
+
+ fid = v9fs_fid_lookup(dentry);
+ dput(dentry);
+ if (IS_ERR(fid)) {
+ ret = PTR_ERR(fid);
+ goto out;
+ }
+
+ ret = p9_client_readlink(fid, &target);
+ p9_fid_put(fid);
+ if (ret)
+ goto out;
+
+ len = strnlen(target, PAGE_SIZE - 1);
+ target[len] = '\0';
+ memcpy_to_folio(folio, 0, target, len);
+ kfree(target);
+
+ ret = 0;
+out:
+ folio_end_read(folio, ret == 0);
+ return ret;
+}
+
+/**
+ * v9fs_vfs_get_link_dotl - follow a symlink path
+ * @dentry: dentry for symlink
+ * @inode: inode for symlink
+ * @done: destructor for return value
+ */
+static const char *
+v9fs_vfs_get_link_dotl(struct dentry *dentry,
+ struct inode *inode,
+ struct delayed_call *done)
+{
+ struct v9fs_session_info *v9ses;
+
+ if (!dentry)
+ return ERR_PTR(-ECHILD);
+
+ v9ses = v9fs_inode2v9ses(inode);
+ if (v9ses->cache & (CACHE_META|CACHE_LOOSE))
+ return page_get_link(dentry, inode, done);
+
+ return v9fs_vfs_get_link_nocache_dotl(dentry, inode, done);
+}
+
int v9fs_refresh_inode_dotl(struct p9_fid *fid, struct inode *inode)
{
struct p9_stat_dotl *st;
@@ -945,6 +1015,10 @@ const struct inode_operations v9fs_file_inode_operations_dotl = {
.set_acl = v9fs_iop_set_acl,
};
+const struct address_space_operations v9fs_symlink_aops_dotl = {
+ .read_folio = v9fs_symlink_read_folio_dotl,
+};
+
const struct inode_operations v9fs_symlink_inode_operations_dotl = {
.get_link = v9fs_vfs_get_link_dotl,
.getattr = v9fs_vfs_getattr_dotl,
--
2.50.1
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