CIFS: Don't let read only caching for mandatory byte-range locked files

If we have mandatory byte-range locks on a file we can't cache reads
because pagereading may have conflicts with these locks on the server.
That's why we should allow level2 oplocks for files without mandatory
locks only.

Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>

4 files changed, 57 insertions, 2 deletions

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index dfab450a191e..e6899cea1c35 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -386,6 +386,7 @@ struct smb_version_values {
         unsigned int    cap_unix;
         unsigned int    cap_nt_find;
         unsigned int    cap_large_files;
+        unsigned int    oplock_read;
 };
 
 #define HEADER_SIZE(server) (server->vals->header_size)
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 22c37254b64e..8ea6ca50a665 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -238,6 +238,23 @@ out:
         return rc;
 }
 
+static bool
+cifs_has_mand_locks(struct cifsInodeInfo *cinode)
+{
+        struct cifs_fid_locks *cur;
+        bool has_locks = false;
+
+        down_read(&cinode->lock_sem);
+        list_for_each_entry(cur, &cinode->llist, llist) {
+                if (!list_empty(&cur->locks)) {
+                        has_locks = true;
+                        break;
+                }
+        }
+        up_read(&cinode->lock_sem);
+        return has_locks;
+}
+
 struct cifsFileInfo *
 cifs_new_fileinfo(struct cifs_fid *fid, struct file *file,
                   struct tcon_link *tlink, __u32 oplock)
@@ -248,6 +265,7 @@ cifs_new_fileinfo(struct cifs_fid *fid, struct file *file,
         struct cifsFileInfo *cfile;
         struct cifs_fid_locks *fdlocks;
         struct cifs_tcon *tcon = tlink_tcon(tlink);
+        struct TCP_Server_Info *server = tcon->ses->server;
 
         cfile = kzalloc(sizeof(struct cifsFileInfo), GFP_KERNEL);
         if (cfile == NULL)
@@ -276,12 +294,22 @@ cifs_new_fileinfo(struct cifs_fid *fid, struct file *file,
         INIT_WORK(&cfile->oplock_break, cifs_oplock_break);
         mutex_init(&cfile->fh_mutex);
 
+        /*
+         * If the server returned a read oplock and we have mandatory brlocks,
+         * set oplock level to None.
+         */
+        if (oplock == server->vals->oplock_read &&
+                                                cifs_has_mand_locks(cinode)) {
+                cFYI(1, "Reset oplock val from read to None due to mand locks");
+                oplock = 0;
+        }
+
         spin_lock(&cifs_file_list_lock);
-        if (fid->pending_open->oplock != CIFS_OPLOCK_NO_CHANGE)
+        if (fid->pending_open->oplock != CIFS_OPLOCK_NO_CHANGE && oplock)
                 oplock = fid->pending_open->oplock;
         list_del(&fid->pending_open->olist);
 
-        tlink_tcon(tlink)->ses->server->ops->set_fid(cfile, fid, oplock);
+        server->ops->set_fid(cfile, fid, oplock);
 
         list_add(&cfile->tlist, &tcon->openFileList);
         /* if readable file instance put first in list*/
@@ -1422,6 +1450,7 @@ cifs_setlk(struct file *file, struct file_lock *flock, __u32 type,
         struct cifsFileInfo *cfile = (struct cifsFileInfo *)file->private_data;
         struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
         struct TCP_Server_Info *server = tcon->ses->server;
+        struct inode *inode = cfile->dentry->d_inode;
 
         if (posix_lck) {
                 int posix_lock_type;
@@ -1459,6 +1488,21 @@ cifs_setlk(struct file *file, struct file_lock *flock, __u32 type,
                 if (!rc)
                         goto out;
 
+                /*
+                 * Windows 7 server can delay breaking lease from read to None
+                 * if we set a byte-range lock on a file - break it explicitly
+                 * before sending the lock to the server to be sure the next
+                 * read won't conflict with non-overlapted locks due to
+                 * pagereading.
+                 */
+                if (!CIFS_I(inode)->clientCanCacheAll &&
+                                        CIFS_I(inode)->clientCanCacheRead) {
+                        cifs_invalidate_mapping(inode);
+                        cFYI(1, "Set no oplock for inode=%p due to mand locks",
+                             inode);
+                        CIFS_I(inode)->clientCanCacheRead = false;
+                }
+
                 rc = server->ops->mand_lock(xid, cfile, flock->fl_start, length,
                                             type, 1, 0, wait_flag);
                 if (rc) {
@@ -3537,6 +3581,13 @@ void cifs_oplock_break(struct work_struct *work)
         struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
         int rc = 0;
 
+        if (!cinode->clientCanCacheAll && cinode->clientCanCacheRead &&
+                                                cifs_has_mand_locks(cinode)) {
+                cFYI(1, "Reset oplock to None for inode=%p due to mand locks",
+                     inode);
+                cinode->clientCanCacheRead = false;
+        }
+
         if (inode && S_ISREG(inode->i_mode)) {
                 if (cinode->clientCanCacheRead)
                         break_lease(inode, O_RDONLY);
diff --git a/fs/cifs/smb1ops.c b/fs/cifs/smb1ops.c
index dd79056c0581..47bc5a87f94e 100644
--- a/fs/cifs/smb1ops.c
+++ b/fs/cifs/smb1ops.c
@@ -959,4 +959,5 @@ struct smb_version_values smb1_values = {
         .cap_unix = CAP_UNIX,
         .cap_nt_find = CAP_NT_SMBS | CAP_NT_FIND,
         .cap_large_files = CAP_LARGE_FILES,
+        .oplock_read = OPLOCK_READ,
 };
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index d79de7bc4435..c9c7aa7ed966 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -708,6 +708,7 @@ struct smb_version_values smb20_values = {
         .cap_unix = 0,
         .cap_nt_find = SMB2_NT_FIND,
         .cap_large_files = SMB2_LARGE_FILES,
+        .oplock_read = SMB2_OPLOCK_LEVEL_II,
 };
 
 struct smb_version_values smb21_values = {
@@ -725,6 +726,7 @@ struct smb_version_values smb21_values = {
         .cap_unix = 0,
         .cap_nt_find = SMB2_NT_FIND,
         .cap_large_files = SMB2_LARGE_FILES,
+        .oplock_read = SMB2_OPLOCK_LEVEL_II,
 };
 
 struct smb_version_values smb30_values = {