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Message-ID: <dfc736a3b22d1a799ec0eb30c038d75120745610.1769013622.git.repk@triplefau.lt>
Date: Wed, 21 Jan 2026 20:56:10 +0100
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: [PATCH v2 3/3] 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/vfs_addr.c | 24 ++++++++++++--
fs/9p/vfs_inode.c | 6 ++--
fs/9p/vfs_inode_dotl.c | 73 +++++++++++++++++++++++++++++++++++++-----
3 files changed, 90 insertions(+), 13 deletions(-)
diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c
index 862164181bac..ee672abbb02c 100644
--- a/fs/9p/vfs_addr.c
+++ b/fs/9p/vfs_addr.c
@@ -70,10 +70,19 @@ static void v9fs_issue_read(struct netfs_io_subrequest *subreq)
{
struct netfs_io_request *rreq = subreq->rreq;
struct p9_fid *fid = rreq->netfs_priv;
+ char *target;
unsigned long long pos = subreq->start + subreq->transferred;
- int total, err;
-
- total = p9_client_read(fid, pos, &subreq->io_iter, &err);
+ int total, err, len, n;
+
+ if (S_ISLNK(rreq->inode->i_mode)) {
+ err = p9_client_readlink(fid, &target);
+ len = strnlen(target, PAGE_SIZE - 1);
+ n = copy_to_iter(target, len, &subreq->io_iter);
+ if (n != len)
+ err = -EFAULT;
+ total = i_size_read(rreq->inode);
+ } else
+ total = p9_client_read(fid, pos, &subreq->io_iter, &err);
/* if we just extended the file size, any portion not in
* cache won't be on server and is zeroes */
@@ -99,6 +108,7 @@ static void v9fs_issue_read(struct netfs_io_subrequest *subreq)
static int v9fs_init_request(struct netfs_io_request *rreq, struct file *file)
{
struct p9_fid *fid;
+ struct dentry *dentry;
bool writing = (rreq->origin == NETFS_READ_FOR_WRITE ||
rreq->origin == NETFS_WRITETHROUGH ||
rreq->origin == NETFS_UNBUFFERED_WRITE ||
@@ -115,6 +125,14 @@ static int v9fs_init_request(struct netfs_io_request *rreq, struct file *file)
if (!fid)
goto no_fid;
p9_fid_get(fid);
+ } else if (S_ISLNK(rreq->inode->i_mode)) {
+ dentry = d_find_alias(rreq->inode);
+ if (!dentry)
+ goto no_fid;
+ fid = v9fs_fid_lookup(dentry);
+ dput(dentry);
+ if (IS_ERR(fid))
+ goto no_fid;
} else {
fid = v9fs_fid_find_inode(rreq->inode, writing, INVALID_UID, true);
if (!fid)
diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index a82a71be309b..e1b762f3e081 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -302,10 +302,12 @@ 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_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 6312b3590f74..486b11dbada3 100644
--- a/fs/9p/vfs_inode_dotl.c
+++ b/fs/9p/vfs_inode_dotl.c
@@ -686,9 +686,13 @@ v9fs_vfs_symlink_dotl(struct mnt_idmap *idmap, struct inode *dir,
int err;
kgid_t gid;
const unsigned char *name;
+ umode_t mode;
+ struct v9fs_session_info *v9ses;
struct p9_qid qid;
struct p9_fid *dfid;
struct p9_fid *fid = NULL;
+ struct inode *inode;
+ struct posix_acl *dacl = NULL, *pacl = NULL;
name = dentry->d_name.name;
p9_debug(P9_DEBUG_VFS, "%lu,%s,%s\n", dir->i_ino, name, symname);
@@ -702,6 +706,15 @@ v9fs_vfs_symlink_dotl(struct mnt_idmap *idmap, struct inode *dir,
gid = v9fs_get_fsgid_for_create(dir);
+ /* Update mode based on ACL value */
+ err = v9fs_acl_mode(dir, &mode, &dacl, &pacl);
+ if (err) {
+ p9_debug(P9_DEBUG_VFS,
+ "Failed to get acl values in symlink %d\n",
+ err);
+ goto error;
+ }
+
/* Server doesn't alter fid on TSYMLINK. Hence no need to clone it. */
err = p9_client_symlink(dfid, name, symname, gid, &qid);
@@ -712,8 +725,30 @@ v9fs_vfs_symlink_dotl(struct mnt_idmap *idmap, struct inode *dir,
v9fs_invalidate_inode_attr(dir);
+ /* instantiate inode and assign the unopened fid to the dentry */
+ fid = p9_client_walk(dfid, 1, &name, 1);
+ if (IS_ERR(fid)) {
+ err = PTR_ERR(fid);
+ p9_debug(P9_DEBUG_VFS, "p9_client_walk failed %d\n",
+ err);
+ goto error;
+ }
+
+ v9ses = v9fs_inode2v9ses(dir);
+ inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
+ if (IS_ERR(inode)) {
+ err = PTR_ERR(inode);
+ p9_debug(P9_DEBUG_VFS, "inode creation failed %d\n",
+ err);
+ goto error;
+ }
+ v9fs_set_create_acl(inode, fid, dacl, pacl);
+ v9fs_fid_add(dentry, &fid);
+ d_instantiate(dentry, inode);
+ err = 0;
error:
p9_fid_put(fid);
+ v9fs_put_acl(dacl, pacl);
p9_fid_put(dfid);
return err;
}
@@ -853,24 +888,23 @@ 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);
@@ -884,6 +918,29 @@ v9fs_vfs_get_link_dotl(struct dentry *dentry,
return target;
}
+/**
+ * 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;
--
2.50.1
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