Merge tag '9p-for-7.2-rc1' of https://github.com/martinetd/linux

1bc18858 · Linus Torvalds <[email protected]> · 2026-06-21 10:26:31 -07:00

Pull 9p updates from Dominique Martinet:
 "Asides of the avalanche of LLM-driven fixes, there are a couple of big
  changes this cycle:

   - negative dentry and symlink cache

   - a way out of the unkillable "io_wait_event_killable" (because it
     looped around waiting for the request flush to come back from
     server; this has been bugging syzcaller folks since forever): I'm
     still not 100% sure about this patch, but I think it's as good as
     we'll ever get, and will keep testing a bit further in the coming
     weeks

  The rest is more noisy than usual, but shouldn't cause any trouble"

* tag '9p-for-7.2-rc1' of https://github.com/martinetd/linux:
  9p: Add missing read barrier in virtio zero-copy path
  net/9p: Replace strlen() strcpy() pair with strscpy()
  9p: skip nlink update in cacheless mode to fix WARN_ON
  net/9p: fix race condition on rdma->state in trans_rdma.c
  9p: v9fs_file_do_lock: replace WARN_ONCE with p9_debug
  9p: Enable symlink caching in page cache
  9p: Set default negative dentry retention time for cache=loose
  9p: Add mount option for negative dentry cache retention
  9p: Cache negative dentries for lookup performance
  9p: avoid returning ERR_PTR(0) from mkdir operations
  9p: avoid putting oldfid in p9_client_walk() error path
  net/9p: fix infinite loop in p9_client_rpc on fatal signal
  docs/filesystems/9p: fix broken external links
  9p: invalidate readdir buffer on seek
  9p: use kvzalloc for readdir buffer
  net/9p/usbg: Constify struct configfs_item_operations

Commit: 1bc18858358d7a4e263a63b59a12cbfd25c16670
Parents: aff3ca32 · aa882786

Merge commit. Changes below are compared with the first parent: aff3ca32.

Changes

18 files changed · +321 −75

File	Status	Add	Del	Content
Documentation/filesystems/9p.rst	modified	+6	−4	View file
fs/9p/fid.c	modified	+6	−5	View file
fs/9p/v9fs.c	modified	+26	−1	View file
fs/9p/v9fs.h	modified	+18	−10	View file
fs/9p/v9fs_vfs.h	modified	+15	−0	View file
fs/9p/vfs_addr.c	modified	+35	−3	View file
fs/9p/vfs_dentry.c	modified	+91	−14	View file
fs/9p/vfs_dir.c	modified	+13	−1	View file
fs/9p/vfs_file.c	modified	+1	−1	View file
fs/9p/vfs_inode.c	modified	+26	−20	View file
fs/9p/vfs_inode_dotl.c	modified	+51	−7	View file
fs/9p/vfs_super.c	modified	+1	−0	View file
include/net/9p/client.h	modified	+2	−0	View file
net/9p/client.c	modified	+5	−2	View file
net/9p/trans_fd.c	modified	+2	−4	View file
net/9p/trans_rdma.c	modified	+17	−2	View file
net/9p/trans_usbg.c	modified	+1	−1	View file
net/9p/trans_virtio.c	modified	+5	−0	View file

Only the first 600 diff lines are shown. Download the complete patch.

Documentation/filesystems/9p.rst

View file

diff --git a/Documentation/filesystems/9p.rst b/Documentation/filesystems/9p.rst
index be3504c..3f65db6 100644
--- a/Documentation/filesystems/9p.rst
+++ b/Documentation/filesystems/9p.rst
@@ -23,13 +23,10 @@ the 9p client is available in the form of a USENIX paper:
 Other applications are described in the following papers:
 
 	* XCPU & Clustering
-	  http://xcpu.org/papers/xcpu-talk.pdf
 	* KVMFS: control file system for KVM
-	  http://xcpu.org/papers/kvmfs.pdf
 	* CellFS: A New Programming Model for the Cell BE
-	  http://xcpu.org/papers/cellfs-talk.pdf
 	* PROSE I/O: Using 9p to enable Application Partitions
-	  http://plan9.escet.urjc.es/iwp9/cready/PROSE_iwp9_2006.pdf
+	  http://web.archive.org/web/20110101152020/http://plan9.escet.urjc.es/iwp9/cready/PROSE_iwp9_2006.pdf
 	* VirtFS: A Virtualization Aware File System pass-through
 	  https://kernel.org/doc/ols/2010/ols2010-pages-109-120.pdf
 
@@ -238,6 +235,11 @@ Options
   cachetag	cache tag to use the specified persistent cache.
 		cache tags for existing cache sessions can be listed at
 		/sys/fs/9p/caches. (applies only to cache=fscache)
+
+  negtimeout    the duration (in milliseconds) that negative dentries (paths
+                that do not actually exist) are retained in the cache. If
+                set to a negative value, those entries are kept indefinitely
+                until evicted by the buffer cache management system
   ============= ===============================================================
 
 Behavior

fs/9p/fid.c

View file

diff --git a/fs/9p/fid.c b/fs/9p/fid.c
index f844122..76242d4 100644
--- a/fs/9p/fid.c
+++ b/fs/9p/fid.c
@@ -20,7 +20,9 @@
 
 static inline void __add_fid(struct dentry *dentry, struct p9_fid *fid)
 {
-	hlist_add_head(&fid->dlist, (struct hlist_head *)&dentry->d_fsdata);
+	struct v9fs_dentry *v9fs_dentry = to_v9fs_dentry(dentry);
+
+	hlist_add_head(&fid->dlist, &v9fs_dentry->head);
 }
 
 
@@ -112,6 +114,7 @@ void v9fs_open_fid_add(struct inode *inode, struct p9_fid **pfid)
 
 static struct p9_fid *v9fs_fid_find(struct dentry *dentry, kuid_t uid, int any)
 {
+	struct v9fs_dentry *v9fs_dentry = to_v9fs_dentry(dentry);
 	struct p9_fid *fid, *ret;
 
 	p9_debug(P9_DEBUG_VFS, " dentry: %pd (%p) uid %d any %d\n",
@@ -119,11 +122,9 @@ static struct p9_fid *v9fs_fid_find(struct dentry *dentry, kuid_t uid, int any)
 		 any);
 	ret = NULL;
 	/* we'll recheck under lock if there's anything to look in */
-	if (dentry->d_fsdata) {
-		struct hlist_head *h = (struct hlist_head *)&dentry->d_fsdata;
-
+	if (!hlist_empty(&v9fs_dentry->head)) {
 		spin_lock(&dentry->d_lock);
-		hlist_for_each_entry(fid, h, dlist) {
+		hlist_for_each_entry(fid, &v9fs_dentry->head, dlist) {
 			if (any || uid_eq(fid->uid, uid)) {
 				ret = fid;
 				p9_fid_get(ret);

fs/9p/v9fs.c

View file

diff --git a/fs/9p/v9fs.c b/fs/9p/v9fs.c
index acda424..274c515 100644
--- a/fs/9p/v9fs.c
+++ b/fs/9p/v9fs.c
@@ -24,6 +24,9 @@
 #include "v9fs_vfs.h"
 #include "cache.h"
 
+/* cache=loose default negative dentry retention time is 24hours */
+#define CACHE_LOOSE_NDENTRY_TIMEOUT_DEFAULT (24 * 60 * 60 * 1000)
+
 static DEFINE_SPINLOCK(v9fs_sessionlist_lock);
 static LIST_HEAD(v9fs_sessionlist);
 struct kmem_cache *v9fs_inode_cache;
@@ -39,7 +42,7 @@ enum {
 	 * source if we rejected it as EINVAL */
 	Opt_source,
 	/* Options that take integer arguments */
-	Opt_debug, Opt_dfltuid, Opt_dfltgid, Opt_afid,
+	Opt_debug, Opt_dfltuid, Opt_dfltgid, Opt_afid, Opt_negtimeout,
 	/* String options */
 	Opt_uname, Opt_remotename, Opt_cache, Opt_cachetag,
 	/* Options that take no arguments */
@@ -93,6 +96,7 @@ const struct fs_parameter_spec v9fs_param_spec[] = {
 	fsparam_string	("access",	Opt_access),
 	fsparam_flag	("posixacl",	Opt_posixacl),
 	fsparam_u32	("locktimeout",	Opt_locktimeout),
+	fsparam_s32	("negtimeout",	Opt_negtimeout),
 
 	/* client options */
 	fsparam_u32	("msize",	Opt_msize),
@@ -159,6 +163,9 @@ int v9fs_show_options(struct seq_file *m, struct dentry *root)
 			   from_kgid_munged(&init_user_ns, v9ses->dfltgid));
 	if (v9ses->afid != ~0)
 		seq_printf(m, ",afid=%u", v9ses->afid);
+	if (v9ses->flags & V9FS_NDENTRY_TIMEOUT_SET)
+		seq_printf(m, ",negtimeout=%d",
+			   (int)v9ses->ndentry_timeout_ms);
 	if (strcmp(v9ses->uname, V9FS_DEFUSER) != 0)
 		seq_printf(m, ",uname=%s", v9ses->uname);
 	if (strcmp(v9ses->aname, V9FS_DEFANAME) != 0)
@@ -337,6 +344,16 @@ int v9fs_parse_param(struct fs_context *fc, struct fs_parameter *param)
 		session_opts->session_lock_timeout = (long)result.uint_32 * HZ;
 		break;
 
+	case Opt_negtimeout:
+		session_opts->flags |= V9FS_NDENTRY_TIMEOUT_SET;
+		if (result.int_32 < 0) {
+			session_opts->ndentry_timeout_ms =
+				NDENTRY_TIMEOUT_NEVER;
+		} else {
+			session_opts->ndentry_timeout_ms = result.int_32;
+		}
+		break;
+
 	/* Options for client */
 	case Opt_msize:
 		if (result.uint_32 < 4096) {
@@ -426,6 +443,14 @@ static void v9fs_apply_options(struct v9fs_session_info *v9ses,
 	v9ses->cache = ctx->session_opts.cache;
 	v9ses->uid = ctx->session_opts.uid;
 	v9ses->session_lock_timeout = ctx->session_opts.session_lock_timeout;
+	v9ses->ndentry_timeout_ms = ctx->session_opts.ndentry_timeout_ms;
+
+	/* If negative dentry timeout has not been overridden set default for
+	 * cache=loose
+	 */
+	if (!(v9ses->flags & V9FS_NDENTRY_TIMEOUT_SET) &&
+	    (v9ses->cache & CACHE_LOOSE))
+		v9ses->ndentry_timeout_ms = CACHE_LOOSE_NDENTRY_TIMEOUT_DEFAULT;
 }
 
 /**

fs/9p/v9fs.h

View file

diff --git a/fs/9p/v9fs.h b/fs/9p/v9fs.h
index 6a12445..a462bcb 100644
--- a/fs/9p/v9fs.h
+++ b/fs/9p/v9fs.h
@@ -24,6 +24,8 @@
  * @V9FS_ACCESS_ANY: use a single attach for all users
  * @V9FS_ACCESS_MASK: bit mask of different ACCESS options
  * @V9FS_POSIX_ACL: POSIX ACLs are enforced
+ * @V9FS_NDENTRY_TIMEOUT_SET: Has negative dentry timeout retention time been
+ *                            overridden by negtimeout mount option
  *
  * Session flags reflect options selected by users at mount time
  */
@@ -34,16 +36,17 @@
 #define V9FS_ACL_MASK V9FS_POSIX_ACL
 
 enum p9_session_flags {
-	V9FS_PROTO_2000U    = 0x01,
-	V9FS_PROTO_2000L    = 0x02,
-	V9FS_ACCESS_SINGLE  = 0x04,
-	V9FS_ACCESS_USER    = 0x08,
-	V9FS_ACCESS_CLIENT  = 0x10,
-	V9FS_POSIX_ACL      = 0x20,
-	V9FS_NO_XATTR       = 0x40,
-	V9FS_IGNORE_QV      = 0x80, /* ignore qid.version for cache hints */
-	V9FS_DIRECT_IO      = 0x100,
-	V9FS_SYNC           = 0x200
+	V9FS_PROTO_2000U         = 0x01,
+	V9FS_PROTO_2000L         = 0x02,
+	V9FS_ACCESS_SINGLE       = 0x04,
+	V9FS_ACCESS_USER         = 0x08,
+	V9FS_ACCESS_CLIENT       = 0x10,
+	V9FS_POSIX_ACL           = 0x20,
+	V9FS_NO_XATTR            = 0x40,
+	V9FS_IGNORE_QV           = 0x80, /* ignore qid.version for cache hints */
+	V9FS_DIRECT_IO           = 0x100,
+	V9FS_SYNC                = 0x200,
+	V9FS_NDENTRY_TIMEOUT_SET = 0x400,
 };
 
 /**
@@ -91,6 +94,7 @@ enum p9_cache_bits {
  * @debug: debug level
  * @afid: authentication handle
  * @cache: cache mode of type &p9_cache_bits
+ * @ndentry_timeout: Negative dentry lookup cache retention time in ms
  * @cachetag: the tag of the cache associated with this session
  * @fscache: session cookie associated with FS-Cache
  * @uname: string user name to mount hierarchy as
@@ -101,6 +105,7 @@ enum p9_cache_bits {
  * @uid: if %V9FS_ACCESS_SINGLE, the numeric uid which mounted the hierarchy
  * @clnt: reference to 9P network client instantiated for this session
  * @slist: reference to list of registered 9p sessions
+ * @ndentry_timeout_ms: Negative dentry caching retention time
  *
  * This structure holds state for each session instance established during
  * a sys_mount() .
@@ -116,6 +121,7 @@ struct v9fs_session_info {
 	unsigned short debug;
 	unsigned int afid;
 	unsigned int cache;
+	unsigned int ndentry_timeout_ms;
 #ifdef CONFIG_9P_FSCACHE
 	char *cachetag;
 	struct fscache_volume *fscache;
@@ -133,6 +139,8 @@ struct v9fs_session_info {
 	long session_lock_timeout; /* retry interval for blocking locks */
 };
 
+#define NDENTRY_TIMEOUT_NEVER (-1U)
+
 /* cache_validity flags */
 #define V9FS_INO_INVALID_ATTR 0x01
 

fs/9p/v9fs_vfs.h

View file

diff --git a/fs/9p/v9fs_vfs.h b/fs/9p/v9fs_vfs.h
index 34c115d..1856d91 100644
--- a/fs/9p/v9fs_vfs.h
+++ b/fs/9p/v9fs_vfs.h
@@ -28,6 +28,19 @@
 /* flags for v9fs_stat2inode() & v9fs_stat2inode_dotl() */
 #define V9FS_STAT2INODE_KEEP_ISIZE 1
 
+/**
+ * struct v9fs_dentry - v9fs specific dentry data
+ * @head: List of fid associated with this dentry
+ * @expire_time: Lookup cache expiration time for negative dentries
+ * @rcu: used by kfree_rcu to schedule clean up job
+ */
+struct v9fs_dentry {
+	struct hlist_head head;
+	u64 expire_time;
+	struct rcu_head rcu;
+};
+#define to_v9fs_dentry(d) ((struct v9fs_dentry *)((d)->d_fsdata))
+
 extern struct file_system_type v9fs_fs_type;
 extern const struct address_space_operations v9fs_addr_operations;
 extern const struct file_operations v9fs_file_operations;
@@ -35,6 +48,8 @@ extern const struct file_operations v9fs_file_operations_dotl;
 extern const struct file_operations v9fs_dir_operations;
 extern const struct file_operations v9fs_dir_operations_dotl;
 extern const struct dentry_operations v9fs_dentry_operations;
+extern void v9fs_ndentry_refresh_timeout(struct dentry *dentry);
+extern void v9fs_dentry_fid_remove(struct dentry *dentry);
 extern const struct dentry_operations v9fs_cached_dentry_operations;
 extern struct kmem_cache *v9fs_inode_cache;
 

fs/9p/vfs_addr.c

View file

diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c
index c21d338..1ac0b3d 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)

fs/9p/vfs_dentry.c

View file

diff --git a/fs/9p/vfs_dentry.c b/fs/9p/vfs_dentry.c
index c5bf74d..e549e22 100644
--- a/fs/9p/vfs_dentry.c
+++ b/fs/9p/vfs_dentry.c
@@ -24,6 +24,46 @@
 #include "fid.h"
 
 /**
+ * v9fs_ndentry_is_expired - Check if negative dentry lookup has expired
+ *
+ * This should be called to know if a negative dentry should be removed from
+ * cache.
+ *
+ * @dentry: dentry in question
+ *
+ */
+static bool v9fs_ndentry_is_expired(struct dentry const *dentry)
+{
+	struct v9fs_session_info *v9ses = v9fs_dentry2v9ses(dentry);
+	struct v9fs_dentry *v9fs_dentry = to_v9fs_dentry(dentry);
+
+	if (v9ses->ndentry_timeout_ms == NDENTRY_TIMEOUT_NEVER)
+		return false;
+
+	return time_before_eq64(v9fs_dentry->expire_time, get_jiffies_64());
+}
+
+/**
+ * v9fs_ndentry_refresh_timeout - Refresh negative dentry lookup cache timeout
+ *
+ * This should be called when a look up yields a negative entry.
+ *
+ * @dentry: dentry in question
+ *
+ */
+void v9fs_ndentry_refresh_timeout(struct dentry *dentry)
+{
+	struct v9fs_session_info *v9ses = v9fs_dentry2v9ses(dentry);
+	struct v9fs_dentry *v9fs_dentry = to_v9fs_dentry(dentry);
+
+	if (v9ses->ndentry_timeout_ms == NDENTRY_TIMEOUT_NEVER)
+		return;
+
+	v9fs_dentry->expire_time = get_jiffies_64() +
+				   msecs_to_jiffies(v9ses->ndentry_timeout_ms);
+}
+
+/**
  * v9fs_cached_dentry_delete - called when dentry refcount equals 0
  * @dentry:  dentry in question
  *
@@ -33,20 +73,15 @@ static int v9fs_cached_dentry_delete(const struct dentry *dentry)
 	p9_debug(P9_DEBUG_VFS, " dentry: %pd (%p)\n",
 		 dentry, dentry);
 
-	/* Don't cache negative dentries */
-	if (d_really_is_negative(dentry))
-		return 1;
-	return 0;
-}
+	if (!d_really_is_negative(dentry))
+		return 0;
 
-/**
- * v9fs_dentry_release - called when dentry is going to be freed
- * @dentry:  dentry that is being release
- *
- */
+	return v9fs_ndentry_is_expired(dentry);
+}
 
-static void v9fs_dentry_release(struct dentry *dentry)
+static void __v9fs_dentry_fid_remove(struct dentry *dentry)
 {
+	struct v9fs_dentry *v9fs_dentry = to_v9fs_dentry(dentry);
 	struct hlist_node *p, *n;
 	struct hlist_head head;
 
@@ -54,13 +89,54 @@ static void v9fs_dentry_release(struct dentry *dentry)
 		 dentry, dentry);
 
 	spin_lock(&dentry->d_lock);
-	hlist_move_list((struct hlist_head *)&dentry->d_fsdata, &head);
+	hlist_move_list(&v9fs_dentry->head, &head);
 	spin_unlock(&dentry->d_lock);
 
 	hlist_for_each_safe(p, n, &head)
 		p9_fid_put(hlist_entry(p, struct p9_fid, dlist));
 }
 
+/**
+ * v9fs_dentry_fid_remove - Release all dentry's fids
+ * @dentry: dentry in question
+ *
+ */
+void v9fs_dentry_fid_remove(struct dentry *dentry)
+{
+	__v9fs_dentry_fid_remove(dentry);
+}
+
+/**
+ * v9fs_dentry_init - Initialize v9fs dentry data
+ * @dentry: dentry in question
+ *
+ */
+static int v9fs_dentry_init(struct dentry *dentry)
+{
+	struct v9fs_dentry *v9fs_dentry = kzalloc(sizeof(*v9fs_dentry),
+						  GFP_KERNEL);
+
+	if (!v9fs_dentry)
+		return -ENOMEM;
+
+	INIT_HLIST_HEAD(&v9fs_dentry->head);
+	dentry->d_fsdata = (void *)v9fs_dentry;
+	return 0;
+}
+
+/**
+ * v9fs_dentry_release - called when dentry is going to be freed
+ * @dentry:  dentry that is being released
+ *
+ */
+static void v9fs_dentry_release(struct dentry *dentry)
+{
+	struct v9fs_dentry *v9fs_dentry = to_v9fs_dentry(dentry);
+
+	__v9fs_dentry_fid_remove(dentry);
+	kfree_rcu(v9fs_dentry, rcu);
+}
+
 static int __v9fs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
 {
 	struct p9_fid *fid;
@@ -72,7 +148,7 @@ static int __v9fs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
 
 	inode = d_inode(dentry);
 	if (!inode)
-		goto out_valid;
+		return !v9fs_ndentry_is_expired(dentry);
 
 	v9inode = V9FS_I(inode);
 	if (v9inode->cache_validity & V9FS_INO_INVALID_ATTR) {
@@ -112,7 +188,6 @@ static int __v9fs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
 			return retval;
 		}
 	}
-out_valid:
 	p9_debug(P9_DEBUG_VFS, "dentry: %pd (%p) is valid\n", dentry, dentry);
 	return 1;
 }
@@ -139,12 +214,14 @@ const struct dentry_operations v9fs_cached_dentry_operations = {
 	.d_revalidate = v9fs_lookup_revalidate,
 	.d_weak_revalidate = __v9fs_lookup_revalidate,
 	.d_delete = v9fs_cached_dentry_delete,
+	.d_init = v9fs_dentry_init,
 	.d_release = v9fs_dentry_release,
 	.d_unalias_trylock = v9fs_dentry_unalias_trylock,
 	.d_unalias_unlock = v9fs_dentry_unalias_unlock,
 };
 
 const struct dentry_operations v9fs_dentry_operations = {
+	.d_init = v9fs_dentry_init,
 	.d_release = v9fs_dentry_release,
 	.d_unalias_trylock = v9fs_dentry_unalias_trylock,
 	.d_unalias_unlock = v9fs_dentry_unalias_unlock,

fs/9p/vfs_dir.c

View file

diff --git a/fs/9p/vfs_dir.c b/fs/9p/vfs_dir.c
index e0d34e4..323f853 100644
--- a/fs/9p/vfs_dir.c
+++ b/fs/9p/vfs_dir.c
@@ -27,6 +27,7 @@
  * struct p9_rdir - readdir accounting
  * @head: start offset of current dirread buffer
  * @tail: end offset of current dirread buffer
+ * @offset: file position the data at @head corresponds to
  * @buf: dirread buffer
  *
  * private structure for keeping track of readdir
@@ -36,6 +37,7 @@
 struct p9_rdir {
 	int head;
 	int tail;
+	loff_t offset;
 	uint8_t buf[];
 };
 
@@ -70,7 +72,7 @@ static struct p9_rdir *v9fs_alloc_rdir_buf(struct file *filp, int buflen)
 	struct p9_fid *fid = filp->private_data;
 
 	if (!fid->rdir)
-		fid->rdir = kzalloc(sizeof(struct p9_rdir) + buflen, GFP_KERNEL);
+		fid->rdir = kvzalloc(sizeof(struct p9_rdir) + buflen, GFP_KERNEL);
 	return fid->rdir;
 }
 
@@ -102,6 +104,9 @@ static int v9fs_dir_readdir(struct file *file, struct dir_context *ctx)
 	kvec.iov_base = rdir->buf;
 	kvec.iov_len = buflen;
 
+	if (rdir->head < rdir->tail && rdir->offset != ctx->pos)
+		rdir->head = rdir->tail = 0;
+
 	while (1) {
 		if (rdir->tail == rdir->head) {
 			struct iov_iter to;
@@ -117,6 +122,7 @@ static int v9fs_dir_readdir(struct file *file, struct dir_context *ctx)
 
 			rdir->head = 0;
 			rdir->tail = n;
+			rdir->offset = ctx->pos;
 		}
 		while (rdir->head < rdir->tail) {
 			err = p9stat_read(fid->clnt, rdir->buf + rdir->head,
@@ -134,6 +140,7 @@ static int v9fs_dir_readdir(struct file *file, struct dir_context *ctx)
 
 			rdir->head += err;
 			ctx->pos += err;
+			rdir->offset = ctx->pos;
 		}
 	}
 }
@@ -161,6 +168,9 @@ static int v9fs_dir_readdir_dotl(struct file *file, struct dir_context *ctx)
 	if (!rdir)
 		return -ENOMEM;
 
+	if (rdir->head < rdir->tail && rdir->offset != ctx->pos)
+		rdir->head = rdir->tail = 0;
+
 	while (1) {
 		if (rdir->tail == rdir->head) {
 			err = p9_client_readdir(fid, rdir->buf, buflen,
@@ -170,6 +180,7 @@ static int v9fs_dir_readdir_dotl(struct file *file, struct dir_context *ctx)
 
 			rdir->head = 0;
 			rdir->tail = err;
+			rdir->offset = ctx->pos;
 		}
 
 		while (rdir->head < rdir->tail) {
@@ -190,6 +201,7 @@ static int v9fs_dir_readdir_dotl(struct file *file, struct dir_context *ctx)
 
 			ctx->pos = curdirent.d_off;
 			rdir->head += err;
+			rdir->offset = ctx->pos;
 		}
 	}
 }

fs/9p/vfs_file.c

View file

diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index c5e73c3..cddfb4b 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -198,7 +198,7 @@ static int v9fs_file_do_lock(struct file *filp, int cmd, struct file_lock *fl)
 		res = -EAGAIN;
 		break;
 	default:
-		WARN_ONCE(1, "unknown lock status code: %d\n", status);
+		p9_debug(P9_DEBUG_ERROR, "unknown lock status code: %d\n", status);
 		fallthrough;
 	case P9_LOCK_ERROR:
 	case P9_LOCK_GRACE:

fs/9p/vfs_inode.c

View file

diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index f468acb..5783d03 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:
@@ -488,10 +490,19 @@ static int v9fs_at_to_dotl_flags(int flags)
  * - ext4 (with dir_nlink feature enabled) sets nlink to 1 if a dir has more
  *   than EXT4_LINK_MAX (65000) links.
  *
+ * In cacheless mode the server is the source of truth for nlink and the
+ * inode is going away immediately, so locally adjusting i_nlink buys
+ * nothing and races with concurrent metadata fetches that may already
+ * have observed the post-unlink value (nlink == 0).