Clarify locking of cifs file and tcon structures and make more granular

Remove the global file_list_lock to simplify cifs/smb3 locking and
have spinlocks that more closely match the information they are
protecting.

Add new tcon->open_file_lock and file->file_info_lock spinlocks.
Locks continue to follow a heirachy,
	cifs_socket --> cifs_ses --> cifs_tcon --> cifs_file
where global tcp_ses_lock still protects socket and cifs_ses, while the
the newer locks protect the lower level structure's information
(tcon and cifs_file respectively).

CC: Stable <stable@vger.kernel.org>
Signed-off-by: Steve French <steve.french@primarydata.com>
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Reviewed-by: Germano Percossi <germano.percossi@citrix.com>

1 files changed, 39 insertions, 27 deletions

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index a95fe8b1afe9..ee5ceae22411 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -305,6 +305,7 @@ cifs_new_fileinfo(struct cifs_fid *fid, struct file *file,
         cfile->tlink = cifs_get_tlink(tlink);
         INIT_WORK(&cfile->oplock_break, cifs_oplock_break);
         mutex_init(&cfile->fh_mutex);
+        spin_lock_init(&cfile->file_info_lock);
 
         cifs_sb_active(inode->i_sb);
 
@@ -317,7 +318,7 @@ cifs_new_fileinfo(struct cifs_fid *fid, struct file *file,
                 oplock = 0;
         }
 
-        spin_lock(&cifs_file_list_lock);
+        spin_lock(&tcon->open_file_lock);
         if (fid->pending_open->oplock != CIFS_OPLOCK_NO_CHANGE && oplock)
                 oplock = fid->pending_open->oplock;
         list_del(&fid->pending_open->olist);
@@ -326,12 +327,13 @@ cifs_new_fileinfo(struct cifs_fid *fid, struct file *file,
         server->ops->set_fid(cfile, fid, oplock);
 
         list_add(&cfile->tlist, &tcon->openFileList);
+
         /* if readable file instance put first in list*/
         if (file->f_mode & FMODE_READ)
                 list_add(&cfile->flist, &cinode->openFileList);
         else
                 list_add_tail(&cfile->flist, &cinode->openFileList);
-        spin_unlock(&cifs_file_list_lock);
+        spin_unlock(&tcon->open_file_lock);
 
         if (fid->purge_cache)
                 cifs_zap_mapping(inode);
@@ -343,16 +345,16 @@ cifs_new_fileinfo(struct cifs_fid *fid, struct file *file,
 struct cifsFileInfo *
 cifsFileInfo_get(struct cifsFileInfo *cifs_file)
 {
-        spin_lock(&cifs_file_list_lock);
+        spin_lock(&cifs_file->file_info_lock);
         cifsFileInfo_get_locked(cifs_file);
-        spin_unlock(&cifs_file_list_lock);
+        spin_unlock(&cifs_file->file_info_lock);
         return cifs_file;
 }
 
 /*
  * Release a reference on the file private data. This may involve closing
  * the filehandle out on the server. Must be called without holding
- * cifs_file_list_lock.
+ * tcon->open_file_lock and cifs_file->file_info_lock.
  */
 void cifsFileInfo_put(struct cifsFileInfo *cifs_file)
 {
@@ -367,11 +369,15 @@ void cifsFileInfo_put(struct cifsFileInfo *cifs_file)
         struct cifs_pending_open open;
         bool oplock_break_cancelled;
 
-        spin_lock(&cifs_file_list_lock);
+        spin_lock(&tcon->open_file_lock);
+
+        spin_lock(&cifs_file->file_info_lock);
         if (--cifs_file->count > 0) {
-                spin_unlock(&cifs_file_list_lock);
+                spin_unlock(&cifs_file->file_info_lock);
+                spin_unlock(&tcon->open_file_lock);
                 return;
         }
+        spin_unlock(&cifs_file->file_info_lock);
 
         if (server->ops->get_lease_key)
                 server->ops->get_lease_key(inode, &fid);
@@ -395,7 +401,8 @@ void cifsFileInfo_put(struct cifsFileInfo *cifs_file)
                         set_bit(CIFS_INO_INVALID_MAPPING, &cifsi->flags);
                 cifs_set_oplock_level(cifsi, 0);
         }
-        spin_unlock(&cifs_file_list_lock);
+
+        spin_unlock(&tcon->open_file_lock);
 
         oplock_break_cancelled = cancel_work_sync(&cifs_file->oplock_break);
 
@@ -772,10 +779,10 @@ int cifs_closedir(struct inode *inode, struct file *file)
         server = tcon->ses->server;
 
         cifs_dbg(FYI, "Freeing private data in close dir\n");
-        spin_lock(&cifs_file_list_lock);
+        spin_lock(&cfile->file_info_lock);
         if (server->ops->dir_needs_close(cfile)) {
                 cfile->invalidHandle = true;
-                spin_unlock(&cifs_file_list_lock);
+                spin_unlock(&cfile->file_info_lock);
                 if (server->ops->close_dir)
                         rc = server->ops->close_dir(xid, tcon, &cfile->fid);
                 else
@@ -784,7 +791,7 @@ int cifs_closedir(struct inode *inode, struct file *file)
                 /* not much we can do if it fails anyway, ignore rc */
                 rc = 0;
         } else
-                spin_unlock(&cifs_file_list_lock);
+                spin_unlock(&cfile->file_info_lock);
 
         buf = cfile->srch_inf.ntwrk_buf_start;
         if (buf) {
@@ -1728,12 +1735,13 @@ struct cifsFileInfo *find_readable_file(struct cifsInodeInfo *cifs_inode,
 {
         struct cifsFileInfo *open_file = NULL;
         struct cifs_sb_info *cifs_sb = CIFS_SB(cifs_inode->vfs_inode.i_sb);
+        struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
 
         /* only filter by fsuid on multiuser mounts */
         if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MULTIUSER))
                 fsuid_only = false;
 
-        spin_lock(&cifs_file_list_lock);
+        spin_lock(&tcon->open_file_lock);
         /* we could simply get the first_list_entry since write-only entries
            are always at the end of the list but since the first entry might
            have a close pending, we go through the whole list */
@@ -1744,8 +1752,8 @@ struct cifsFileInfo *find_readable_file(struct cifsInodeInfo *cifs_inode,
                         if (!open_file->invalidHandle) {
                                 /* found a good file */
                                 /* lock it so it will not be closed on us */
-                                cifsFileInfo_get_locked(open_file);
-                                spin_unlock(&cifs_file_list_lock);
+                                cifsFileInfo_get(open_file);
+                                spin_unlock(&tcon->open_file_lock);
                                 return open_file;
                         } /* else might as well continue, and look for
                              another, or simply have the caller reopen it
@@ -1753,7 +1761,7 @@ struct cifsFileInfo *find_readable_file(struct cifsInodeInfo *cifs_inode,
                 } else /* write only file */
                         break; /* write only files are last so must be done */
         }
-        spin_unlock(&cifs_file_list_lock);
+        spin_unlock(&tcon->open_file_lock);
         return NULL;
 }
 
@@ -1762,6 +1770,7 @@ struct cifsFileInfo *find_writable_file(struct cifsInodeInfo *cifs_inode,
 {
         struct cifsFileInfo *open_file, *inv_file = NULL;
         struct cifs_sb_info *cifs_sb;
+        struct cifs_tcon *tcon;
         bool any_available = false;
         int rc;
         unsigned int refind = 0;
@@ -1777,15 +1786,16 @@ struct cifsFileInfo *find_writable_file(struct cifsInodeInfo *cifs_inode,
         }
 
         cifs_sb = CIFS_SB(cifs_inode->vfs_inode.i_sb);
+        tcon = cifs_sb_master_tcon(cifs_sb);
 
         /* only filter by fsuid on multiuser mounts */
         if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MULTIUSER))
                 fsuid_only = false;
 
-        spin_lock(&cifs_file_list_lock);
+        spin_lock(&tcon->open_file_lock);
 refind_writable:
         if (refind > MAX_REOPEN_ATT) {
-                spin_unlock(&cifs_file_list_lock);
+                spin_unlock(&tcon->open_file_lock);
                 return NULL;
         }
         list_for_each_entry(open_file, &cifs_inode->openFileList, flist) {
@@ -1796,8 +1806,8 @@ refind_writable:
                 if (OPEN_FMODE(open_file->f_flags) & FMODE_WRITE) {
                         if (!open_file->invalidHandle) {
                                 /* found a good writable file */
-                                cifsFileInfo_get_locked(open_file);
-                                spin_unlock(&cifs_file_list_lock);
+                                cifsFileInfo_get(open_file);
+                                spin_unlock(&tcon->open_file_lock);
                                 return open_file;
                         } else {
                                 if (!inv_file)
@@ -1813,24 +1823,24 @@ refind_writable:
 
         if (inv_file) {
                 any_available = false;
-                cifsFileInfo_get_locked(inv_file);
+                cifsFileInfo_get(inv_file);
         }
 
-        spin_unlock(&cifs_file_list_lock);
+        spin_unlock(&tcon->open_file_lock);
 
         if (inv_file) {
                 rc = cifs_reopen_file(inv_file, false);
                 if (!rc)
                         return inv_file;
                 else {
-                        spin_lock(&cifs_file_list_lock);
+                        spin_lock(&tcon->open_file_lock);
                         list_move_tail(&inv_file->flist,
                                         &cifs_inode->openFileList);
-                        spin_unlock(&cifs_file_list_lock);
+                        spin_unlock(&tcon->open_file_lock);
                         cifsFileInfo_put(inv_file);
-                        spin_lock(&cifs_file_list_lock);
                         ++refind;
                         inv_file = NULL;
+                        spin_lock(&tcon->open_file_lock);
                         goto refind_writable;
                 }
         }
@@ -3612,15 +3622,17 @@ static int cifs_readpage(struct file *file, struct page *page)
 static int is_inode_writable(struct cifsInodeInfo *cifs_inode)
 {
         struct cifsFileInfo *open_file;
+        struct cifs_tcon *tcon =
+                cifs_sb_master_tcon(CIFS_SB(cifs_inode->vfs_inode.i_sb));
 
-        spin_lock(&cifs_file_list_lock);
+        spin_lock(&tcon->open_file_lock);
         list_for_each_entry(open_file, &cifs_inode->openFileList, flist) {
                 if (OPEN_FMODE(open_file->f_flags) & FMODE_WRITE) {
-                        spin_unlock(&cifs_file_list_lock);
+                        spin_unlock(&tcon->open_file_lock);
                         return 1;
                 }
         }
-        spin_unlock(&cifs_file_list_lock);
+        spin_unlock(&tcon->open_file_lock);
         return 0;
 }