diff options
Diffstat (limited to 'fs/direct-io.c')
| -rw-r--r-- | fs/direct-io.c | 74 |
1 files changed, 20 insertions, 54 deletions
diff --git a/fs/direct-io.c b/fs/direct-io.c index a10cb91cade..51f270b479b 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -1136,8 +1136,27 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode, return ret; } +/* + * This is a library function for use by filesystem drivers. + * + * The locking rules are governed by the flags parameter: + * - if the flags value contains DIO_LOCKING we use a fancy locking + * scheme for dumb filesystems. + * For writes this function is called under i_mutex and returns with + * i_mutex held, for reads, i_mutex is not held on entry, but it is + * taken and dropped again before returning. + * For reads and writes i_alloc_sem is taken in shared mode and released + * on I/O completion (which may happen asynchronously after returning to + * the caller). + * + * - if the flags value does NOT contain DIO_LOCKING we don't use any + * internal locking but rather rely on the filesystem to synchronize + * direct I/O reads/writes versus each other and truncate. + * For reads and writes both i_mutex and i_alloc_sem are not held on + * entry and are never taken. + */ ssize_t -__blockdev_direct_IO_newtrunc(int rw, struct kiocb *iocb, struct inode *inode, +__blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, struct block_device *bdev, const struct iovec *iov, loff_t offset, unsigned long nr_segs, get_block_t get_block, dio_iodone_t end_io, dio_submit_t submit_io, int flags) @@ -1233,57 +1252,4 @@ __blockdev_direct_IO_newtrunc(int rw, struct kiocb *iocb, struct inode *inode, out: return retval; } -EXPORT_SYMBOL(__blockdev_direct_IO_newtrunc); - -/* - * This is a library function for use by filesystem drivers. - * - * The locking rules are governed by the flags parameter: - * - if the flags value contains DIO_LOCKING we use a fancy locking - * scheme for dumb filesystems. - * For writes this function is called under i_mutex and returns with - * i_mutex held, for reads, i_mutex is not held on entry, but it is - * taken and dropped again before returning. - * For reads and writes i_alloc_sem is taken in shared mode and released - * on I/O completion (which may happen asynchronously after returning to - * the caller). - * - * - if the flags value does NOT contain DIO_LOCKING we don't use any - * internal locking but rather rely on the filesystem to synchronize - * direct I/O reads/writes versus each other and truncate. - * For reads and writes both i_mutex and i_alloc_sem are not held on - * entry and are never taken. - */ -ssize_t -__blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, - struct block_device *bdev, const struct iovec *iov, loff_t offset, - unsigned long nr_segs, get_block_t get_block, dio_iodone_t end_io, - dio_submit_t submit_io, int flags) -{ - ssize_t retval; - - retval = __blockdev_direct_IO_newtrunc(rw, iocb, inode, bdev, iov, - offset, nr_segs, get_block, end_io, submit_io, flags); - /* - * In case of error extending write may have instantiated a few - * blocks outside i_size. Trim these off again for DIO_LOCKING. - * NOTE: DIO_NO_LOCK/DIO_OWN_LOCK callers have to handle this in - * their own manner. This is a further example of where the old - * truncate sequence is inadequate. - * - * NOTE: filesystems with their own locking have to handle this - * on their own. - */ - if (flags & DIO_LOCKING) { - if (unlikely((rw & WRITE) && retval < 0)) { - loff_t isize = i_size_read(inode); - loff_t end = offset + iov_length(iov, nr_segs); - - if (end > isize) - vmtruncate(inode, isize); - } - } - - return retval; -} EXPORT_SYMBOL(__blockdev_direct_IO); |