From: Remi Pommarel Date: Thu, 21 May 2026 09:40:32 +0000 (+0200) Subject: 9p: Enable symlink caching in page cache X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=712da38d134b6681946368dd5c9400b43eb772b0;p=thirdparty%2Fkernel%2Flinux.git 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 Message-ID: <982462d17c0c0d2856763266a25eb04d080c1dbb.1779355927.git.repk@triplefau.lt> Signed-off-by: Dominique Martinet --- diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c index 862164181bac..2b6ca573f955 100644 --- a/fs/9p/vfs_addr.c +++ b/fs/9p/vfs_addr.c @@ -70,11 +70,34 @@ 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 = 0, err, len, n; + + if (S_ISLNK(rreq->inode->i_mode)) { + /* p9_client_readlink() must not be called for legacy protocols + * 9p2000 or 9p2000.u. + */ + BUG_ON(!p9_is_proto_dotl(fid->clnt)); + if (WARN_ON_ONCE(pos)) { + /* reading a link at a non null offset should + * not happen + */ + err = -EIO; + goto fill_subreq; + } + err = p9_client_readlink(fid, &target); + if (err != 0) + goto fill_subreq; + len = strlen(target); + n = copy_to_iter(target, len, &subreq->io_iter); + kfree(target); + total = n; + } else { + total = p9_client_read(fid, pos, &subreq->io_iter, &err); + } +fill_subreq: /* if we just extended the file size, any portion not in * cache won't be on server and is zeroes */ if (subreq->rreq->origin != NETFS_UNBUFFERED_READ && @@ -99,6 +122,7 @@ 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 +139,14 @@ 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_any_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 a178e8cb2c82..cdaa5034cbef 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 fae324681ff3..8b056c334c2b 100644 --- a/fs/9p/vfs_inode_dotl.c +++ b/fs/9p/vfs_inode_dotl.c @@ -686,9 +686,11 @@ v9fs_vfs_symlink_dotl(struct mnt_idmap *idmap, struct inode *dir, int err; kgid_t gid; const unsigned char *name; + struct v9fs_session_info *v9ses; struct p9_qid qid; struct p9_fid *dfid; struct p9_fid *fid = NULL; + struct inode *inode; name = dentry->d_name.name; p9_debug(P9_DEBUG_VFS, "%lu,%s,%s\n", dir->i_ino, name, symname); @@ -712,6 +714,26 @@ 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_fid_add(dentry, &fid); + d_instantiate(dentry, inode); + err = 0; error: p9_fid_put(fid); p9_fid_put(dfid); @@ -853,16 +875,18 @@ error: } /** - * 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; @@ -884,6 +908,26 @@ 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; + + 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;