Revert "CIFS: Fix write after setting a read lock for read oplock files"

that solution has data races and can end up two identical writes to the
server: when clientCanCacheAll value can be changed during the execution
of __generic_file_aio_write.

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

3 files changed, 31 insertions, 65 deletions

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index f653835d067b..de7f9168a118 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -228,7 +228,6 @@ cifs_alloc_inode(struct super_block *sb)
         cifs_set_oplock_level(cifs_inode, 0);
         cifs_inode->delete_pending = false;
         cifs_inode->invalid_mapping = false;
-        cifs_inode->leave_pages_clean = false;
         cifs_inode->vfs_inode.i_blkbits = 14;  /* 2**14 = CIFS_MAX_MSGSIZE */
         cifs_inode->server_eof = 0;
         cifs_inode->uniqueid = 0;
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index aea1eec64911..dfab450a191e 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -1030,7 +1030,6 @@ struct cifsInodeInfo {
         bool clientCanCacheAll;         /* read and writebehind oplock */
         bool delete_pending;            /* DELETE_ON_CLOSE is set */
         bool invalid_mapping;           /* pagecache is invalid */
-        bool leave_pages_clean; /* protected by i_mutex, not set pages dirty */
         unsigned long time;             /* jiffies of last update of inode */
         u64  server_eof;                /* current file size on server -- protected by i_lock */
         u64  uniqueid;                  /* server inode number */
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 0a6677ba212b..1b322d041f1e 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2103,15 +2103,7 @@ static int cifs_write_end(struct file *file, struct address_space *mapping,
         } else {
                 rc = copied;
                 pos += copied;
-                /*
-                 * When we use strict cache mode and cifs_strict_writev was run
-                 * with level II oplock (indicated by leave_pages_clean field of
-                 * CIFS_I(inode)), we can leave pages clean - cifs_strict_writev
-                 * sent the data to the server itself.
-                 */
-                if (!CIFS_I(inode)->leave_pages_clean ||
-                    !(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_STRICT_IO))
-                        set_page_dirty(page);
+                set_page_dirty(page);
         }
 
         if (rc > 0) {
@@ -2462,8 +2454,8 @@ ssize_t cifs_user_writev(struct kiocb *iocb, const struct iovec *iov,
 }
 
 static ssize_t
-cifs_pagecache_writev(struct kiocb *iocb, const struct iovec *iov,
-                      unsigned long nr_segs, loff_t pos, bool cache_ex)
+cifs_writev(struct kiocb *iocb, const struct iovec *iov,
+            unsigned long nr_segs, loff_t pos)
 {
         struct file *file = iocb->ki_filp;
         struct cifsFileInfo *cfile = (struct cifsFileInfo *)file->private_data;
@@ -2485,12 +2477,8 @@ cifs_pagecache_writev(struct kiocb *iocb, const struct iovec *iov,
                                      server->vals->exclusive_lock_type, NULL,
                                      CIFS_WRITE_OP)) {
                 mutex_lock(&inode->i_mutex);
-                if (!cache_ex)
-                        cinode->leave_pages_clean = true;
                 rc = __generic_file_aio_write(iocb, iov, nr_segs,
-                                              &iocb->ki_pos);
-                if (!cache_ex)
-                        cinode->leave_pages_clean = false;
+                                               &iocb->ki_pos);
                 mutex_unlock(&inode->i_mutex);
         }
 
@@ -2517,62 +2505,42 @@ cifs_strict_writev(struct kiocb *iocb, const struct iovec *iov,
         struct cifsFileInfo *cfile = (struct cifsFileInfo *)
                                                 iocb->ki_filp->private_data;
         struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
-        ssize_t written, written2;
+
+#ifdef CONFIG_CIFS_SMB2
         /*
-         * We need to store clientCanCacheAll here to prevent race
-         * conditions - this value can be changed during an execution
-         * of generic_file_aio_write. For CIFS it can be changed from
-         * true to false only, but for SMB2 it can be changed both from
-         * true to false and vice versa. So, we can end up with a data
-         * stored in the cache, not marked dirty and not sent to the
-         * server if this value changes its state from false to true
-         * after cifs_write_end.
+         * If we have an oplock for read and want to write a data to the file
+         * we need to store it in the page cache and then push it to the server
+         * to be sure the next read will get a valid data.
          */
-        bool cache_ex = cinode->clientCanCacheAll;
-        bool cache_read = cinode->clientCanCacheRead;
-        int rc;
-        loff_t saved_pos;
+        if (!cinode->clientCanCacheAll && cinode->clientCanCacheRead) {
+                ssize_t written;
+                int rc;
+
+                written = generic_file_aio_write(iocb, iov, nr_segs, pos);
+                rc = filemap_fdatawrite(inode->i_mapping);
+                if (rc)
+                        return (ssize_t)rc;
 
-        if (cache_ex) {
-                if (cap_unix(tcon->ses) &&
-                    ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0) &&
-                    (CIFS_UNIX_FCNTL_CAP & le64_to_cpu(
-                                                tcon->fsUnixInfo.Capability)))
-                        return generic_file_aio_write(iocb, iov, nr_segs, pos);
-                return cifs_pagecache_writev(iocb, iov, nr_segs, pos, cache_ex);
+                return written;
         }
+#endif
 
         /*
-         * For files without exclusive oplock in strict cache mode we need to
-         * write the data to the server exactly from the pos to pos+len-1 rather
-         * than flush all affected pages because it may cause a error with
-         * mandatory locks on these pages but not on the region from pos to
-         * ppos+len-1.
+         * For non-oplocked files in strict cache mode we need to write the data
+         * to the server exactly from the pos to pos+len-1 rather than flush all
+         * affected pages because it may cause a error with mandatory locks on
+         * these pages but not on the region from pos to ppos+len-1.
          */
-        written = cifs_user_writev(iocb, iov, nr_segs, pos);
-        if (!cache_read || written <= 0)
-                return written;
 
-        saved_pos = iocb->ki_pos;
-        iocb->ki_pos = pos;
-        /* we have a read oplock - need to store a data in the page cache */
+        if (!cinode->clientCanCacheAll)
+                return cifs_user_writev(iocb, iov, nr_segs, pos);
+
         if (cap_unix(tcon->ses) &&
-            ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0) &&
-            (CIFS_UNIX_FCNTL_CAP & le64_to_cpu(
-                                        tcon->fsUnixInfo.Capability)))
-                written2 = generic_file_aio_write(iocb, iov, nr_segs, pos);
-        else
-                written2 = cifs_pagecache_writev(iocb, iov, nr_segs, pos,
-                                                 cache_ex);
-        /* errors occured during writing - invalidate the page cache */
-        if (written2 < 0) {
-                rc = cifs_invalidate_mapping(inode);
-                if (rc)
-                        written = (ssize_t)rc;
-                else
-                        iocb->ki_pos = saved_pos;
-        }
-        return written;
+            (CIFS_UNIX_FCNTL_CAP & le64_to_cpu(tcon->fsUnixInfo.Capability)) &&
+            ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0))
+                return generic_file_aio_write(iocb, iov, nr_segs, pos);
+
+        return cifs_writev(iocb, iov, nr_segs, pos);
 }
 
 static struct cifs_readdata *