[PATCH] tail data corruption on mempressure

[PATCH] tail data corruption on mempressure

[Oleg Drokin]

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Hello!

    This patch fixes a bug when mmap-write to a file tail and subsequent read cause written data to be lost
    due to page-cache interacting mistake in low number of free buffers situation.
    Please apply.

Bye,
     Oleg

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--- linux/fs/reiserfs/inode.c.orig	Thu Dec 20 11:07:05 2001
+++ linux/fs/reiserfs/inode.c	Thu Dec 20 19:03:51 2001
@@ -325,6 +325,16 @@
     */
     if (buffer_uptodate(bh_result)) {
         goto finished ;
+    } else 
+	/*
+	** grab_tail_page can trigger calls to reiserfs_get_block on up to date
+	** pages without any buffers.  If the page is up to date, we don't want
+	** read old data off disk.  Set the up to date bit on the buffer instead
+	** and jump to the end
+	*/
+	    if (Page_Uptodate(bh_result->b_page)) {
+		mark_buffer_uptodate(bh_result, 1);
+		goto finished ;
     }
 
     // read file tail into part of page
@@ -833,7 +843,7 @@
 	}
 	if (retval == POSITION_FOUND) {
 	    reiserfs_warning ("vs-825: reiserfs_get_block: "
-			      "%k should not be found\n", &key);
+			      "%K should not be found\n", &key);
 	    retval = -EEXIST;
 	    if (allocated_block_nr)
 	        reiserfs_free_block (&th, allocated_block_nr);