7 files changed, 55 insertions, 32 deletions

diff --git a/fs/9p/v9fs_vfs.h b/fs/9p/v9fs_vfs.h
index 5a0db6dec8d1..aaee1e6584e6 100644
--- a/fs/9p/v9fs_vfs.h
+++ b/fs/9p/v9fs_vfs.h
@@ -40,6 +40,9 @@
  */
 #define P9_LOCK_TIMEOUT (30*HZ)
 
+/* flags for v9fs_stat2inode() & v9fs_stat2inode_dotl() */
+#define V9FS_STAT2INODE_KEEP_ISIZE 1
+
 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;
@@ -61,8 +64,10 @@ int v9fs_init_inode(struct v9fs_session_info *v9ses,
                     struct inode *inode, umode_t mode, dev_t);
 void v9fs_evict_inode(struct inode *inode);
 ino_t v9fs_qid2ino(struct p9_qid *qid);
-void v9fs_stat2inode(struct p9_wstat *, struct inode *, struct super_block *);
-void v9fs_stat2inode_dotl(struct p9_stat_dotl *, struct inode *);
+void v9fs_stat2inode(struct p9_wstat *stat, struct inode *inode,
+                      struct super_block *sb, unsigned int flags);
+void v9fs_stat2inode_dotl(struct p9_stat_dotl *stat, struct inode *inode,
+                           unsigned int flags);
 int v9fs_dir_release(struct inode *inode, struct file *filp);
 int v9fs_file_open(struct inode *inode, struct file *file);
 void v9fs_inode2stat(struct inode *inode, struct p9_wstat *stat);
@@ -83,4 +88,18 @@ static inline void v9fs_invalidate_inode_attr(struct inode *inode)
 }
 
 int v9fs_open_to_dotl_flags(int flags);
+
+static inline void v9fs_i_size_write(struct inode *inode, loff_t i_size)
+{
+        /*
+         * 32-bit need the lock, concurrent updates could break the
+         * sequences and make i_size_read() loop forever.
+         * 64-bit updates are atomic and can skip the locking.
+         */
+        if (sizeof(i_size) > sizeof(long))
+                spin_lock(&inode->i_lock);
+        i_size_write(inode, i_size);
+        if (sizeof(i_size) > sizeof(long))
+                spin_unlock(&inode->i_lock);
+}
 #endif
diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index a25efa782fcc..9a1125305d84 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -446,7 +446,11 @@ v9fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
                 i_size = i_size_read(inode);
                 if (iocb->ki_pos > i_size) {
                         inode_add_bytes(inode, iocb->ki_pos - i_size);
-                        i_size_write(inode, iocb->ki_pos);
+                        /*
+                         * Need to serialize against i_size_write() in
+                         * v9fs_stat2inode()
+                         */
+                        v9fs_i_size_write(inode, iocb->ki_pos);
                 }
                 return retval;
         }
diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 85ff859d3af5..72b779bc0942 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -538,7 +538,7 @@ static struct inode *v9fs_qid_iget(struct super_block *sb,
         if (retval)
                 goto error;
 
-        v9fs_stat2inode(st, inode, sb);
+        v9fs_stat2inode(st, inode, sb, 0);
         v9fs_cache_inode_get_cookie(inode);
         unlock_new_inode(inode);
         return inode;
@@ -1092,7 +1092,7 @@ v9fs_vfs_getattr(const struct path *path, struct kstat *stat,
         if (IS_ERR(st))
                 return PTR_ERR(st);
 
-        v9fs_stat2inode(st, d_inode(dentry), dentry->d_sb);
+        v9fs_stat2inode(st, d_inode(dentry), dentry->d_sb, 0);
         generic_fillattr(d_inode(dentry), stat);
 
         p9stat_free(st);
@@ -1170,12 +1170,13 @@ static int v9fs_vfs_setattr(struct dentry *dentry, struct iattr *iattr)
  * @stat: Plan 9 metadata (mistat) structure
  * @inode: inode to populate
  * @sb: superblock of filesystem
+ * @flags: control flags (e.g. V9FS_STAT2INODE_KEEP_ISIZE)
  *
  */
 
 void
 v9fs_stat2inode(struct p9_wstat *stat, struct inode *inode,
-        struct super_block *sb)
+                 struct super_block *sb, unsigned int flags)
 {
         umode_t mode;
         char ext[32];
@@ -1216,10 +1217,11 @@ v9fs_stat2inode(struct p9_wstat *stat, struct inode *inode,
         mode = p9mode2perm(v9ses, stat);
         mode |= inode->i_mode & ~S_IALLUGO;
         inode->i_mode = mode;
-        i_size_write(inode, stat->length);
 
+        if (!(flags & V9FS_STAT2INODE_KEEP_ISIZE))
+                v9fs_i_size_write(inode, stat->length);
         /* not real number of blocks, but 512 byte ones ... */
-        inode->i_blocks = (i_size_read(inode) + 512 - 1) >> 9;
+        inode->i_blocks = (stat->length + 512 - 1) >> 9;
         v9inode->cache_validity &= ~V9FS_INO_INVALID_ATTR;
 }
 
@@ -1416,9 +1418,9 @@ int v9fs_refresh_inode(struct p9_fid *fid, struct inode *inode)
 {
         int umode;
         dev_t rdev;
-        loff_t i_size;
         struct p9_wstat *st;
         struct v9fs_session_info *v9ses;
+        unsigned int flags;
 
         v9ses = v9fs_inode2v9ses(inode);
         st = p9_client_stat(fid);
@@ -1431,16 +1433,13 @@ int v9fs_refresh_inode(struct p9_fid *fid, struct inode *inode)
         if ((inode->i_mode & S_IFMT) != (umode & S_IFMT))
                 goto out;
 
-        spin_lock(&inode->i_lock);
         /*
          * We don't want to refresh inode->i_size,
          * because we may have cached data
          */
-        i_size = inode->i_size;
-        v9fs_stat2inode(st, inode, inode->i_sb);
-        if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
-                inode->i_size = i_size;
-        spin_unlock(&inode->i_lock);
+        flags = (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) ?
+                V9FS_STAT2INODE_KEEP_ISIZE : 0;
+        v9fs_stat2inode(st, inode, inode->i_sb, flags);
 out:
         p9stat_free(st);
         kfree(st);
diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c
index 4823e1c46999..a950a927a626 100644
--- a/fs/9p/vfs_inode_dotl.c
+++ b/fs/9p/vfs_inode_dotl.c
@@ -143,7 +143,7 @@ static struct inode *v9fs_qid_iget_dotl(struct super_block *sb,
         if (retval)
                 goto error;
 
-        v9fs_stat2inode_dotl(st, inode);
+        v9fs_stat2inode_dotl(st, inode, 0);
         v9fs_cache_inode_get_cookie(inode);
         retval = v9fs_get_acl(inode, fid);
         if (retval)
@@ -496,7 +496,7 @@ v9fs_vfs_getattr_dotl(const struct path *path, struct kstat *stat,
         if (IS_ERR(st))
                 return PTR_ERR(st);
 
-        v9fs_stat2inode_dotl(st, d_inode(dentry));
+        v9fs_stat2inode_dotl(st, d_inode(dentry), 0);
         generic_fillattr(d_inode(dentry), stat);
         /* Change block size to what the server returned */
         stat->blksize = st->st_blksize;
@@ -607,11 +607,13 @@ int v9fs_vfs_setattr_dotl(struct dentry *dentry, struct iattr *iattr)
  * v9fs_stat2inode_dotl - populate an inode structure with stat info
  * @stat: stat structure
  * @inode: inode to populate
+ * @flags: ctrl flags (e.g. V9FS_STAT2INODE_KEEP_ISIZE)
  *
  */
 
 void
-v9fs_stat2inode_dotl(struct p9_stat_dotl *stat, struct inode *inode)
+v9fs_stat2inode_dotl(struct p9_stat_dotl *stat, struct inode *inode,
+                      unsigned int flags)
 {
         umode_t mode;
         struct v9fs_inode *v9inode = V9FS_I(inode);
@@ -631,7 +633,8 @@ v9fs_stat2inode_dotl(struct p9_stat_dotl *stat, struct inode *inode)
                 mode |= inode->i_mode & ~S_IALLUGO;
                 inode->i_mode = mode;
 
-                i_size_write(inode, stat->st_size);
+                if (!(flags & V9FS_STAT2INODE_KEEP_ISIZE))
+                        v9fs_i_size_write(inode, stat->st_size);
                 inode->i_blocks = stat->st_blocks;
         } else {
                 if (stat->st_result_mask & P9_STATS_ATIME) {
@@ -661,8 +664,9 @@ v9fs_stat2inode_dotl(struct p9_stat_dotl *stat, struct inode *inode)
                 }
                 if (stat->st_result_mask & P9_STATS_RDEV)
                         inode->i_rdev = new_decode_dev(stat->st_rdev);
-                if (stat->st_result_mask & P9_STATS_SIZE)
-                        i_size_write(inode, stat->st_size);
+                if (!(flags & V9FS_STAT2INODE_KEEP_ISIZE) &&
+                    stat->st_result_mask & P9_STATS_SIZE)
+                        v9fs_i_size_write(inode, stat->st_size);
                 if (stat->st_result_mask & P9_STATS_BLOCKS)
                         inode->i_blocks = stat->st_blocks;
         }
@@ -928,9 +932,9 @@ v9fs_vfs_get_link_dotl(struct dentry *dentry,
 
 int v9fs_refresh_inode_dotl(struct p9_fid *fid, struct inode *inode)
 {
-        loff_t i_size;
         struct p9_stat_dotl *st;
         struct v9fs_session_info *v9ses;
+        unsigned int flags;
 
         v9ses = v9fs_inode2v9ses(inode);
         st = p9_client_getattr_dotl(fid, P9_STATS_ALL);
@@ -942,16 +946,13 @@ int v9fs_refresh_inode_dotl(struct p9_fid *fid, struct inode *inode)
         if ((inode->i_mode & S_IFMT) != (st->st_mode & S_IFMT))
                 goto out;
 
-        spin_lock(&inode->i_lock);
         /*
          * We don't want to refresh inode->i_size,
          * because we may have cached data
          */
-        i_size = inode->i_size;
-        v9fs_stat2inode_dotl(st, inode);
-        if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
-                inode->i_size = i_size;
-        spin_unlock(&inode->i_lock);
+        flags = (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) ?
+                V9FS_STAT2INODE_KEEP_ISIZE : 0;
+        v9fs_stat2inode_dotl(st, inode, flags);
 out:
         kfree(st);
         return 0;
diff --git a/fs/9p/vfs_super.c b/fs/9p/vfs_super.c
index 10d3bd3f534b..d13d35cf69c0 100644
--- a/fs/9p/vfs_super.c
+++ b/fs/9p/vfs_super.c
@@ -172,7 +172,7 @@ static struct dentry *v9fs_mount(struct file_system_type *fs_type, int flags,
                         goto release_sb;
                 }
                 d_inode(root)->i_ino = v9fs_qid2ino(&st->qid);
-                v9fs_stat2inode_dotl(st, d_inode(root));
+                v9fs_stat2inode_dotl(st, d_inode(root), 0);
                 kfree(st);
         } else {
                 struct p9_wstat *st = NULL;
@@ -183,7 +183,7 @@ static struct dentry *v9fs_mount(struct file_system_type *fs_type, int flags,
                 }
 
                 d_inode(root)->i_ino = v9fs_qid2ino(&st->qid);
-                v9fs_stat2inode(st, d_inode(root), sb);
+                v9fs_stat2inode(st, d_inode(root), sb, 0);
 
                 p9stat_free(st);
                 kfree(st);
diff --git a/net/9p/client.c b/net/9p/client.c
index 357214a51f13..b85d51f4b8eb 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -1061,7 +1061,7 @@ struct p9_client *p9_client_create(const char *dev_name, char *options)
                 p9_debug(P9_DEBUG_ERROR,
                          "Please specify a msize of at least 4k\n");
                 err = -EINVAL;
-                goto free_client;
+                goto close_trans;
         }
 
         err = p9_client_version(clnt);
diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c
index e2fbf3677b9b..29420ebb8f07 100644
--- a/net/9p/trans_xen.c
+++ b/net/9p/trans_xen.c
@@ -513,7 +513,7 @@ static void xen_9pfs_front_changed(struct xenbus_device *dev,
         case XenbusStateClosed:
                 if (dev->state == XenbusStateClosed)
                         break;
-                /* Missed the backend's CLOSING state -- fallthrough */
+                /* fall through - Missed the backend's CLOSING state */
         case XenbusStateClosing:
                 xenbus_frontend_closed(dev);
                 break;