#include <linux/namei.h>
#include <linux/uio.h>
#include <linux/bio.h>
+#include <linux/workqueue.h>
#include "ext4_jbd2.h"
#include "xattr.h"
}
/*
+ * O_DIRECT for ext3 (or indirect map) based files
+ *
* If the O_DIRECT write will extend the file then add this inode to the
* orphan list. So recovery will truncate it back to the original size
* if the machine crashes during the write.
* crashes then stale disk data _may_ be exposed inside the file. But current
* VFS code falls back into buffered path in that case so we are safe.
*/
-static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,
+static ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb,
const struct iovec *iov, loff_t offset,
unsigned long nr_segs)
{
return ret;
}
+/* Maximum number of blocks we map for direct IO at once. */
+
+static int ext4_get_block_dio_write(struct inode *inode, sector_t iblock,
+ struct buffer_head *bh_result, int create)
+{
+ handle_t *handle = NULL;
+ int ret = 0;
+ unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
+ int dio_credits;
+
+ /*
+ * DIO VFS code passes create = 0 flag for write to
+ * the middle of file. It does this to avoid block
+ * allocation for holes, to prevent expose stale data
+ * out when there is parallel buffered read (which does
+ * not hold the i_mutex lock) while direct IO write has
+ * not completed. DIO request on holes finally falls back
+ * to buffered IO for this reason.
+ *
+ * For ext4 extent based file, since we support fallocate,
+ * new allocated extent as uninitialized, for holes, we
+ * could fallocate blocks for holes, thus parallel
+ * buffered IO read will zero out the page when read on
+ * a hole while parallel DIO write to the hole has not completed.
+ *
+ * when we come here, we know it's a direct IO write to
+ * to the middle of file (<i_size)
+ * so it's safe to override the create flag from VFS.
+ */
+ create = EXT4_GET_BLOCKS_DIO_CREATE_EXT;
+
+ if (max_blocks > DIO_MAX_BLOCKS)
+ max_blocks = DIO_MAX_BLOCKS;
+ dio_credits = ext4_chunk_trans_blocks(inode, max_blocks);
+ handle = ext4_journal_start(inode, dio_credits);
+ if (IS_ERR(handle)) {
+ ret = PTR_ERR(handle);
+ goto out;
+ }
+ ret = ext4_get_blocks(handle, inode, iblock, max_blocks, bh_result,
+ create);
+ if (ret > 0) {
+ bh_result->b_size = (ret << inode->i_blkbits);
+ ret = 0;
+ }
+ ext4_journal_stop(handle);
+out:
+ return ret;
+}
+
+#define DIO_AIO 0x1
+
+static void ext4_free_io_end(ext4_io_end_t *io)
+{
+ kfree(io);
+}
+
+/*
+ * IO write completion for unwritten extents.
+ *
+ * check a range of space and convert unwritten extents to written.
+ */
+static void ext4_end_dio_unwritten(struct work_struct *work)
+{
+ ext4_io_end_t *io = container_of(work, ext4_io_end_t, work);
+ struct inode *inode = io->inode;
+ loff_t offset = io->offset;
+ size_t size = io->size;
+ int ret = 0;
+ int aio = io->flag & DIO_AIO;
+
+ if (aio)
+ mutex_lock(&inode->i_mutex);
+ if (offset + size <= i_size_read(inode))
+ ret = ext4_convert_unwritten_extents(inode, offset, size);
+
+ if (ret < 0)
+ printk(KERN_EMERG "%s: failed to convert unwritten"
+ "extents to written extents, error is %d\n",
+ __func__, ret);
+
+ ext4_free_io_end(io);
+ if (aio)
+ mutex_unlock(&inode->i_mutex);
+}
+
+static ext4_io_end_t *ext4_init_io_end (struct inode *inode, unsigned int flag)
+{
+ ext4_io_end_t *io = NULL;
+
+ io = kmalloc(sizeof(*io), GFP_NOFS);
+
+ if (io) {
+ io->inode = inode;
+ io->flag = flag;
+ io->offset = 0;
+ io->size = 0;
+ io->error = 0;
+ INIT_WORK(&io->work, ext4_end_dio_unwritten);
+ }
+
+ return io;
+}
+
+static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
+ ssize_t size, void *private)
+{
+ ext4_io_end_t *io_end = iocb->private;
+ struct workqueue_struct *wq;
+
+ /* if not hole or unwritten extents, just simple return */
+ if (!io_end || !size || !iocb->private)
+ return;
+ io_end->offset = offset;
+ io_end->size = size;
+ wq = EXT4_SB(io_end->inode->i_sb)->dio_unwritten_wq;
+
+ /* We need to convert unwritten extents to written */
+ queue_work(wq, &io_end->work);
+
+ if (is_sync_kiocb(iocb))
+ flush_workqueue(wq);
+
+ iocb->private = NULL;
+}
+/*
+ * For ext4 extent files, ext4 will do direct-io write to holes,
+ * preallocated extents, and those write extend the file, no need to
+ * fall back to buffered IO.
+ *
+ * For holes, we fallocate those blocks, mark them as unintialized
+ * If those blocks were preallocated, we mark sure they are splited, but
+ * still keep the range to write as unintialized.
+ *
+ * When end_io call back function called at the last IO complete time,
+ * those extents will be converted to written extents.
+ *
+ * If the O_DIRECT write will extend the file then add this inode to the
+ * orphan list. So recovery will truncate it back to the original size
+ * if the machine crashes during the write.
+ *
+ */
+static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
+ const struct iovec *iov, loff_t offset,
+ unsigned long nr_segs)
+{
+ struct file *file = iocb->ki_filp;
+ struct inode *inode = file->f_mapping->host;
+ ssize_t ret;
+ size_t count = iov_length(iov, nr_segs);
+
+ loff_t final_size = offset + count;
+ if (rw == WRITE && final_size <= inode->i_size) {
+ /*
+ * For DIO we fallocate blocks for holes, we fallocate blocks
+ * The fallocated extent for hole is marked as uninitialized
+ * to prevent paralel buffered read to expose the stale data
+ * before DIO complete the data IO.
+ * as for previously fallocated extents, ext4 get_block
+ * will just simply mark the buffer mapped but still
+ * keep the extents uninitialized.
+ *
+ * At the end of IO, the ext4 end_io callback function
+ * will convert those unwritten extents to written,
+ *
+ */
+ iocb->private = ext4_init_io_end(inode, !is_sync_kiocb(iocb));
+ if (!iocb->private)
+ return -ENOMEM;
+ ret = blockdev_direct_IO(rw, iocb, inode,
+ inode->i_sb->s_bdev, iov,
+ offset, nr_segs,
+ ext4_get_block_dio_write,
+ ext4_end_io_dio);
+ return ret;
+ }
+ return ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs);
+}
+
+static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,
+ const struct iovec *iov, loff_t offset,
+ unsigned long nr_segs)
+{
+ struct file *file = iocb->ki_filp;
+ struct inode *inode = file->f_mapping->host;
+
+ if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)
+ return ext4_ext_direct_IO(rw, iocb, iov, offset, nr_segs);
+
+ return ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs);
+}
+
/*
* Pages can be marked dirty completely asynchronously from ext4's journalling
* activity. By filemap_sync_pte(), try_to_unmap_one(), etc. We cannot do
git://ftp.safe.ca / safe / jmp / linux-2.6 / commitdiff