[PATCH] Prevent deadlock in JFS when flushing data during commit

This prevents a deadlock in JFS.

diff --git a/fs/jfs/jfs_txnmgr.c b/fs/jfs/jfs_txnmgr.c
index 986feb874a12926431226895edfe23a445f27e81..47b4b1f763f18b10a089a2e14ebc503cbcebd99e 100644 (file)
--- a/fs/jfs/jfs_txnmgr.c
+++ b/fs/jfs/jfs_txnmgr.c
@@ -1155,19 +1155,30 @@ int txCommit(tid_t tid,         /* transaction identifier */
                jfs_ip = JFS_IP(ip);
 
                /*
-                * BUGBUG - Should we call filemap_fdatawrite here instead
-                * of fsync_inode_data?
-                * If we do, we have a deadlock condition since we may end
-                * up recursively calling jfs_get_block with the IWRITELOCK
-                * held.  We may be able to do away with IWRITELOCK while
-                * committing transactions and use i_sem instead.
+                * BUGBUG - This code has temporarily been removed.  The
+                * intent is to ensure that any file data is written before
+                * the metadata is committed to the journal.  This prevents
+                * uninitialized data from appearing in a file after the
+                * journal has been replayed.  (The uninitialized data
+                * could be sensitive data removed by another user.)
+                *
+                * The problem now is that we are holding the IWRITELOCK
+                * on the inode, and calling filemap_fdatawrite on an
+                * unmapped page will cause a deadlock in jfs_get_block.
+                *
+                * The long term solution is to pare down the use of
+                * IWRITELOCK.  We are currently holding it too long.
+                * We could also be smarter about which data pages need
+                * to be written before the transaction is committed and
+                * when we don't need to worry about it at all.
+                *
+                * if ((!S_ISDIR(ip->i_mode))
+                *    && (tblk->flag & COMMIT_DELETE) == 0) {
+                *      filemap_fdatawait(ip->i_mapping);
+                *      filemap_fdatawrite(ip->i_mapping);
+                *      filemap_fdatawait(ip->i_mapping);
+                * }
                 */
-               if ((!S_ISDIR(ip->i_mode))
-                   && (tblk->flag & COMMIT_DELETE) == 0) {
-                       filemap_fdatawait(ip->i_mapping);
-                       filemap_fdatawrite(ip->i_mapping);
-                       filemap_fdatawait(ip->i_mapping);
-               }
 
                /*
                 * Mark inode as not dirty.  It will still be on the dirty