xfs: Fix overallocation in xfs_buf_allocate_memory()
authorJan Kara <jack@suse.cz>
Tue, 5 Jun 2012 22:32:26 +0000 (00:32 +0200)
committerBen Myers <bpm@sgi.com>
Thu, 21 Jun 2012 18:38:25 +0000 (13:38 -0500)
commitbcf62ab64d1ba257dd9d4283a077a7219a05073a
treeb4de28d5e5978de675440e966384f0c4c01ff0e3
parent079da28c64ebeca357adae77aea3ae7160e45d98
xfs: Fix overallocation in xfs_buf_allocate_memory()

Commit de1cbee which removed b_file_offset in favor of b_bn introduced a bug
causing xfs_buf_allocate_memory() to overestimate the number of necessary
pages. The problem is that xfs_buf_alloc() sets b_bn to -1 and thus effectively
every buffer is straddling a page boundary which causes
xfs_buf_allocate_memory() to allocate two pages and use vmalloc() for access
which is unnecessary.

Dave says xfs_buf_alloc() doesn't need to set b_bn to -1 anymore since the
buffer is inserted into the cache only after being fully initialized now.
So just make xfs_buf_alloc() fill in proper block number from the beginning.

CC: David Chinner <dchinner@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
fs/xfs/xfs_buf.c