[PATCH] reiserfs highmem bug on tail reads

From: Chris Mason (mason@suse.com)
Date: Thu Apr 26 2001 - 00:51:11 EST


Ok, so all the reiserfs tail bugs weren't quite fixed yet, the last
tail fix can cause problems with highmem turned on. Both bugs are
in fs/reiserfs/inode.c:_get_block_create_0

When reading the tail in, if the buffer was already up to date,
we skip the disk i/o and return. But the cleanup code assumes the
page was kmap'd, which isn't right.

Also, there was a chance to double kmap the page if kmap scheduled a
nd the tree balanced while we slept. This bug has been there for
a long time.

Anyway, this was tested with Andrea's HIGHMEM_DEBUG_MERE_MORTALS
patch to force highmem on my 128MB machine. It works for me, but
more testers are always good.

-chris

against 2.4.4-pre6, should work against 2.4.3 or higher.

diff -Nru a/fs/reiserfs/inode.c b/fs/reiserfs/inode.c
--- a/fs/reiserfs/inode.c Wed Apr 25 23:15:14 2001
+++ b/fs/reiserfs/inode.c Wed Apr 25 23:15:14 2001
@@ -374,9 +374,11 @@
     ** sure we need to. But, this means the item might move if
     ** kmap schedules
     */
- p = (char *)kmap(bh_result->b_page) ;
- if (fs_changed (fs_gen, inode->i_sb) && item_moved (&tmp_ih, &path)) {
- goto research;
+ if (!p) {
+ p = (char *)kmap(bh_result->b_page) ;
+ if (fs_changed (fs_gen, inode->i_sb) && item_moved (&tmp_ih, &path)) {
+ goto research;
+ }
     }
     p += offset ;
     memset (p, 0, inode->i_sb->s_blocksize);
@@ -420,14 +422,15 @@
         ih = get_ih (&path);
     } while (1);
 
+ flush_dcache_page(bh_result->b_page) ;
+ kunmap(bh_result->b_page) ;
+
 finished:
     pathrelse (&path);
     bh_result->b_blocknr = 0 ;
     bh_result->b_dev = inode->i_dev;
     mark_buffer_uptodate (bh_result, 1);
     bh_result->b_state |= (1UL << BH_Mapped);
- flush_dcache_page(bh_result->b_page) ;
- kunmap(bh_result->b_page) ;
     return 0;
 }
 

-
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This archive was generated by hypermail 2b29 : Mon Apr 30 2001 - 21:00:15 EST