From: Stephen Tweedie <sct@redhat.com>
Lock buffers before initialising their contents to avoid any risk of being
overwritten by the results of a parallel read.
Signed-off-by: Stephen Tweedie <sct@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/fs/ext3/resize.c | 15 +++++++++++----
1 files changed, 11 insertions(+), 4 deletions(-)
diff -puN fs/ext3/resize.c~ext3-online-resize-lock-newly-created-buffers fs/ext3/resize.c
--- 25/fs/ext3/resize.c~ext3-online-resize-lock-newly-created-buffers Thu Sep 30 17:32:49 2004
+++ 25-akpm/fs/ext3/resize.c Thu Sep 30 17:32:49 2004
@@ -118,12 +118,15 @@ static struct buffer_head *bclean(handle
int err;
bh = sb_getblk(sb, blk);
- set_buffer_uptodate(bh);
if ((err = ext3_journal_get_write_access(handle, bh))) {
brelse(bh);
bh = ERR_PTR(err);
- } else
+ } else {
+ lock_buffer(bh);
memset(bh->b_data, 0, sb->s_blocksize);
+ set_buffer_uptodate(bh);
+ unlock_buffer(bh);
+ }
return bh;
}
@@ -201,12 +204,14 @@ static int setup_new_group_blocks(struct
ext3_debug("update backup group %#04lx (+%d)\n", block, bit);
gdb = sb_getblk(sb, block);
- set_buffer_uptodate(gdb);
if ((err = ext3_journal_get_write_access(handle, gdb))) {
brelse(gdb);
goto exit_bh;
}
+ lock_buffer(bh);
memcpy(gdb->b_data, sbi->s_group_desc[i], bh->b_size);
+ set_buffer_uptodate(gdb);
+ unlock_buffer(bh);
ext3_journal_dirty_metadata(handle, gdb);
ext3_set_bit(bit, bh->b_data);
brelse(gdb);
@@ -642,14 +647,16 @@ static void update_backups(struct super_
break;
bh = sb_getblk(sb, group * bpg + blk_off);
- set_buffer_uptodate(bh);
ext3_debug(sb, __FUNCTION__, "update metadata backup %#04lx\n",
bh->b_blocknr);
if ((err = ext3_journal_get_write_access(handle, bh)))
break;
+ lock_buffer(bh);
memcpy(bh->b_data, data, size);
if (rest)
memset(bh->b_data + size, 0, rest);
+ set_buffer_uptodate(bh);
+ unlock_buffer(bh);
ext3_journal_dirty_metadata(handle, bh);
brelse(bh);
}
_