diff options
Diffstat (limited to 'fs/direct-io.c')
| -rw-r--r-- | fs/direct-io.c | 40 |
1 files changed, 26 insertions, 14 deletions
diff --git a/fs/direct-io.c b/fs/direct-io.c index 7dde0df8e8b6..4012885d027f 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -97,6 +97,18 @@ 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(). */ @@ -108,22 +120,16 @@ 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 */ }; /* @@ -1144,10 +1150,16 @@ __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)); dio->flags = flags; if (dio->flags & DIO_LOCKING) { @@ -1197,7 +1209,7 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, if (dio->flags & DIO_LOCKING) { if (unlikely((rw & WRITE) && retval < 0)) { loff_t isize = i_size_read(inode); - if (end > isize ) + if (end > isize) vmtruncate(inode, isize); } } |