diff options
| -rw-r--r-- | fs/direct-io.c | 38 |
1 files changed, 25 insertions, 13 deletions
diff --git a/fs/direct-io.c b/fs/direct-io.c index b912270..9f34bb9 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -104,6 +104,18 @@ struct dio { unsigned cur_page_len; /* Nr of bytes at cur_page_offset */ sector_t cur_page_block; /* Where it starts */ + /* BIO completion state */ + spinlock_t bio_lock; /* protects BIO fields below */ + unsigned long refcount; /* direct_io_worker() and bios */ + struct bio *bio_list; /* singly linked via bi_private */ + struct task_struct *waiter; /* waiting task (NULL if none) */ + + /* AIO related stuff */ + struct kiocb *iocb; /* kiocb */ + int is_async; /* is IO async ? */ + int io_error; /* IO error in completion path */ + ssize_t result; /* IO result */ + /* * Page fetching state. These variables belong to dio_refill_pages(). */ @@ -115,22 +127,16 @@ struct dio { * Page queue. These variables belong to dio_refill_pages() and * dio_get_page(). */ - struct page *pages[DIO_PAGES]; /* page buffer */ unsigned head; /* next page to process */ unsigned tail; /* last valid page + 1 */ int page_errors; /* errno from get_user_pages() */ - /* BIO completion state */ - spinlock_t bio_lock; /* protects BIO fields below */ - unsigned long refcount; /* direct_io_worker() and bios */ - struct bio *bio_list; /* singly linked via bi_private */ - struct task_struct *waiter; /* waiting task (NULL if none) */ - - /* AIO related stuff */ - struct kiocb *iocb; /* kiocb */ - int is_async; /* is IO async ? */ - int io_error; /* IO error in completion path */ - ssize_t result; /* IO result */ + /* + * pages[] (and any fields placed after it) are not zeroed out at + * allocation time. Don't add new fields after pages[] unless you + * wish that they not be zeroed. + */ + struct page *pages[DIO_PAGES]; /* page buffer */ }; /* @@ -1151,10 +1157,16 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, } } - dio = kzalloc(sizeof(*dio), GFP_KERNEL); + dio = kmalloc(sizeof(*dio), GFP_KERNEL); retval = -ENOMEM; if (!dio) goto out; + /* + * Believe it or not, zeroing out the page array caused a .5% + * performance regression in a database benchmark. So, we take + * care to only zero out what's needed. + */ + memset(dio, 0, offsetof(struct dio, pages)); /* * For block device access DIO_NO_LOCKING is used, |
