diff options
| author | David Chinner <dgc@sgi.com> | 2007-02-12 00:51:41 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-02-12 09:48:27 -0800 |
| commit | 33a266dda9fbbe72dd978a451a8ee33c59da5e9c (patch) | |
| tree | 7e3fa4100e436f12b4c0ed562dd1f6dc9ec84fd4 /fs/buffer.c | |
| parent | 42da9cbd3eedde33a42acc2cb06f454814cf5de0 (diff) | |
| download | lwn-33a266dda9fbbe72dd978a451a8ee33c59da5e9c.tar.gz lwn-33a266dda9fbbe72dd978a451a8ee33c59da5e9c.zip | |
[PATCH] Make BH_Unwritten a first class bufferhead flag V2
Currently, XFS uses BH_PrivateStart for flagging unwritten extent state in a
bufferhead. Recently, I found the long standing mmap/unwritten extent
conversion bug, and it was to do with partial page invalidation not clearing
the unwritten flag from bufferheads attached to the page but beyond EOF. See
here for a full explaination:
http://oss.sgi.com/archives/xfs/2006-12/msg00196.html
The solution I have checked into the XFS dev tree involves duplicating code
from block_invalidatepage to clear the unwritten flag from the bufferhead(s),
and then calling block_invalidatepage() to do the rest.
Christoph suggested that this would be better solved by pushing the unwritten
flag into the common buffer head flags and just adding the call to
discard_buffer():
http://oss.sgi.com/archives/xfs/2006-12/msg00239.html
The following patch makes BH_Unwritten a first class citizen.
Signed-off-by: Dave Chinner <dgc@sgi.com>
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/buffer.c')
| -rw-r--r-- | fs/buffer.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/fs/buffer.c b/fs/buffer.c index 7ff6e9346fae..a4b824234fb9 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -1440,6 +1440,7 @@ static void discard_buffer(struct buffer_head * bh) clear_buffer_req(bh); clear_buffer_new(bh); clear_buffer_delay(bh); + clear_buffer_unwritten(bh); unlock_buffer(bh); } @@ -1823,6 +1824,7 @@ static int __block_prepare_write(struct inode *inode, struct page *page, continue; } if (!buffer_uptodate(bh) && !buffer_delay(bh) && + !buffer_unwritten(bh) && (block_start < from || block_end > to)) { ll_rw_block(READ, 1, &bh); *wait_bh++=bh; @@ -2544,7 +2546,7 @@ int block_truncate_page(struct address_space *mapping, if (PageUptodate(page)) set_buffer_uptodate(bh); - if (!buffer_uptodate(bh) && !buffer_delay(bh)) { + if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) { err = -EIO; ll_rw_block(READ, 1, &bh); wait_on_buffer(bh); |