Fix kernel oops when CONFIG_DEBUG_ATOMIC_SLEEP is enabled.

Removed oplock_break_received flag which was added to achieve
synchronization between oplock handler and open handler by earlier commit.

It is not needed because there is an existing lock open_file_lock to achieve
the same. find_readable_file takes open_file_lock and then traverses the
openFileList. Similarly, cifs_oplock_break while closing the deferred
handle (i.e cifsFileInfo_put) takes open_file_lock and then sends close
to the server.

Added comments for better readability.

Signed-off-by: Rohith Surabattula <rohiths@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index d7ea9c5..2ffcb29 100644 (file)
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -133,7 +133,7 @@ struct workqueue_struct     *cifsiod_wq;
 struct workqueue_struct        *decrypt_wq;
 struct workqueue_struct        *fileinfo_put_wq;
 struct workqueue_struct        *cifsoplockd_wq;
-struct workqueue_struct *deferredclose_wq;
+struct workqueue_struct        *deferredclose_wq;
 __u32 cifs_lock_secret;
 
 /*

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index d88b4b5..ea90c53 100644 (file)
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -1257,8 +1257,7 @@ struct cifsFileInfo {
        struct work_struct oplock_break; /* work for oplock breaks */
        struct work_struct put; /* work for the final part of _put */
        struct delayed_work deferred;
-       bool oplock_break_received; /* Flag to indicate oplock break */
-       bool deferred_scheduled;
+       bool deferred_close_scheduled; /* Flag to indicate close is scheduled */
 };
 
 struct cifs_io_parms {

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 6caad10..304d9d3 100644 (file)
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -323,8 +323,7 @@ cifs_new_fileinfo(struct cifs_fid *fid, struct file *file,
        cfile->dentry = dget(dentry);
        cfile->f_flags = file->f_flags;
        cfile->invalidHandle = false;
-       cfile->oplock_break_received = false;
-       cfile->deferred_scheduled = false;
+       cfile->deferred_close_scheduled = false;
        cfile->tlink = cifs_get_tlink(tlink);
        INIT_WORK(&cfile->oplock_break, cifs_oplock_break);
        INIT_WORK(&cfile->put, cifsFileInfo_put_work);
@@ -574,21 +573,18 @@ int cifs_open(struct inode *inode, struct file *file)
                        file->f_op = &cifs_file_direct_ops;
        }
 
-       spin_lock(&CIFS_I(inode)->deferred_lock);
        /* Get the cached handle as SMB2 close is deferred */
        rc = cifs_get_readable_path(tcon, full_path, &cfile);
        if (rc == 0) {
                if (file->f_flags == cfile->f_flags) {
                        file->private_data = cfile;
+                       spin_lock(&CIFS_I(inode)->deferred_lock);
                        cifs_del_deferred_close(cfile);
                        spin_unlock(&CIFS_I(inode)->deferred_lock);
                        goto out;
                } else {
-                       spin_unlock(&CIFS_I(inode)->deferred_lock);
                        _cifsFileInfo_put(cfile, true, false);
                }
-       } else {
-               spin_unlock(&CIFS_I(inode)->deferred_lock);
        }
 
        if (server->oplocks)
@@ -878,12 +874,12 @@ void smb2_deferred_work_close(struct work_struct *work)
                        struct cifsFileInfo, deferred.work);
 
        spin_lock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);
-       if (!cfile->deferred_scheduled) {
+       if (!cfile->deferred_close_scheduled) {
                spin_unlock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);
                return;
        }
        cifs_del_deferred_close(cfile);
-       cfile->deferred_scheduled = false;
+       cfile->deferred_close_scheduled = false;
        spin_unlock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);
        _cifsFileInfo_put(cfile, true, false);
 }
@@ -905,14 +901,15 @@ int cifs_close(struct inode *inode, struct file *file)
                                inode->i_ctime = inode->i_mtime = current_time(inode);
                        spin_lock(&cinode->deferred_lock);
                        cifs_add_deferred_close(cfile, dclose);
-                       if (cfile->deferred_scheduled) {
+                       if (cfile->deferred_close_scheduled &&
+                           delayed_work_pending(&cfile->deferred)) {
                                mod_delayed_work(deferredclose_wq,
                                                &cfile->deferred, cifs_sb->ctx->acregmax);
                        } else {
                                /* Deferred close for files */
                                queue_delayed_work(deferredclose_wq,
                                                &cfile->deferred, cifs_sb->ctx->acregmax);
-                               cfile->deferred_scheduled = true;
+                               cfile->deferred_close_scheduled = true;
                                spin_unlock(&cinode->deferred_lock);
                                return 0;
                        }
@@ -2020,8 +2017,7 @@ struct cifsFileInfo *find_readable_file(struct cifsInodeInfo *cifs_inode,
                if (fsuid_only && !uid_eq(open_file->uid, current_fsuid()))
                        continue;
                if (OPEN_FMODE(open_file->f_flags) & FMODE_READ) {
-                       if ((!open_file->invalidHandle) &&
-                               (!open_file->oplock_break_received)) {
+                       if ((!open_file->invalidHandle)) {
                                /* found a good file */
                                /* lock it so it will not be closed on us */
                                cifsFileInfo_get(open_file);
@@ -4874,13 +4870,14 @@ oplock_break_ack:
        }
        /*
         * When oplock break is received and there are no active
-        * file handles but cached, then set the flag oplock_break_received.
+        * file handles but cached, then schedule deferred close immediately.
         * So, new open will not use cached handle.
         */
        spin_lock(&CIFS_I(inode)->deferred_lock);
        is_deferred = cifs_is_deferred_close(cfile, &dclose);
-       if (is_deferred && cfile->deferred_scheduled) {
-               cfile->oplock_break_received = true;
+       if (is_deferred &&
+           cfile->deferred_close_scheduled &&
+           delayed_work_pending(&cfile->deferred)) {
                mod_delayed_work(deferredclose_wq, &cfile->deferred, 0);
        }
        spin_unlock(&CIFS_I(inode)->deferred_lock);

diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index 801a530..34f2a7e 100644 (file)
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -672,6 +672,9 @@ cifs_add_pending_open(struct cifs_fid *fid, struct tcon_link *tlink,
        spin_unlock(&tlink_tcon(open->tlink)->open_file_lock);
 }
 
+/*
+ * Critical section which runs after acquiring deferred_lock.
+ */
 bool
 cifs_is_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close **pdclose)
 {
@@ -688,6 +691,9 @@ cifs_is_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close **
        return false;
 }
 
+/*
+ * Critical section which runs after acquiring deferred_lock.
+ */
 void
 cifs_add_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close *dclose)
 {
@@ -707,6 +713,9 @@ cifs_add_deferred_close(struct cifsFileInfo *cfile, struct cifs_deferred_close *
        list_add_tail(&dclose->dlist, &CIFS_I(d_inode(cfile->dentry))->deferred_closes);
 }
 
+/*
+ * Critical section which runs after acquiring deferred_lock.
+ */
 void
 cifs_del_deferred_close(struct cifsFileInfo *cfile)
 {