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authorZach Brown <zach.brown@oracle.com>2007-08-20 17:12:01 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-08-20 22:50:25 -0700
commit848c4dd5153c7a0de55470ce99a8e13a63b4703f (patch)
tree4defb21d98037a96a3a90e83eaf85a10b46f0571 /fs/direct-io.c
parent38f061c5714265fa8481cc0b7795aa8fe81b45be (diff)
downloadvexpress-lsk-848c4dd5153c7a0de55470ce99a8e13a63b4703f.tar.gz
dio: zero struct dio with kzalloc instead of manually
This patch uses kzalloc to zero all of struct dio rather than manually trying to track which fields we rely on being zero. It passed aio+dio stress testing and some bug regression testing on ext3. This patch was introduced by Linus in the conversation that lead up to Badari's minimal fix to manually zero .map_bh.b_state in commit: 6a648fa72161d1f6468dabd96c5d3c0db04f598a It makes the code a bit smaller. Maybe a couple fewer cachelines to load, if we're lucky: text data bss dec hex filename 3285925 568506 1304616 5159047 4eb887 vmlinux 3285797 568506 1304616 5158919 4eb807 vmlinux.patched I was unable to measure a stable difference in the number of cpu cycles spent in blockdev_direct_IO() when pushing aio+dio 256K reads at ~340MB/s. So the resulting intent of the patch isn't a performance gain but to avoid exposing ourselves to the risk of finding another field like .map_bh.b_state where we rely on zeroing but don't enforce it in the code. Signed-off-by: Zach Brown <zach.brown@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/direct-io.c')
-rw-r--r--fs/direct-io.c18
1 files changed, 1 insertions, 17 deletions
diff --git a/fs/direct-io.c b/fs/direct-io.c
index 6874785bb65..901dc55e9f5 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -958,36 +958,22 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode,
ssize_t ret2;
size_t bytes;
- dio->bio = NULL;
dio->inode = inode;
dio->rw = rw;
dio->blkbits = blkbits;
dio->blkfactor = inode->i_blkbits - blkbits;
- dio->start_zero_done = 0;
- dio->size = 0;
dio->block_in_file = offset >> blkbits;
- dio->blocks_available = 0;
- dio->cur_page = NULL;
- dio->boundary = 0;
- dio->reap_counter = 0;
dio->get_block = get_block;
dio->end_io = end_io;
- dio->map_bh.b_private = NULL;
- dio->map_bh.b_state = 0;
dio->final_block_in_bio = -1;
dio->next_block_for_io = -1;
- dio->page_errors = 0;
- dio->io_error = 0;
- dio->result = 0;
dio->iocb = iocb;
dio->i_size = i_size_read(inode);
spin_lock_init(&dio->bio_lock);
dio->refcount = 1;
- dio->bio_list = NULL;
- dio->waiter = NULL;
/*
* In case of non-aligned buffers, we may need 2 more
@@ -995,8 +981,6 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode,
*/
if (unlikely(dio->blkfactor))
dio->pages_in_io = 2;
- else
- dio->pages_in_io = 0;
for (seg = 0; seg < nr_segs; seg++) {
user_addr = (unsigned long)iov[seg].iov_base;
@@ -1184,7 +1168,7 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
}
}
- dio = kmalloc(sizeof(*dio), GFP_KERNEL);
+ dio = kzalloc(sizeof(*dio), GFP_KERNEL);
retval = -ENOMEM;
if (!dio)
goto out;