};
/*
- * xfs_file_dio_write - handle direct IO writes
- *
- * Lock the inode appropriately to prepare for and issue a direct IO write.
- * By separating it from the buffered write path we remove all the tricky to
- * follow locking changes and looping.
- *
- * If there are cached pages or we're extending the file, we need IOLOCK_EXCL
- * until we're sure the bytes at the new EOF have been zeroed and/or the cached
- * pages are flushed out.
- *
- * In most cases the direct IO writes will be done holding IOLOCK_SHARED
- * allowing them to be done in parallel with reads and other direct IO writes.
- * However, if the IO is not aligned to filesystem blocks, the direct IO layer
- * needs to do sub-block zeroing and that requires serialisation against other
- * direct IOs to the same block. In this case we need to serialise the
- * submission of the unaligned IOs so that we don't get racing block zeroing in
- * the dio layer. To avoid the problem with aio, we also need to wait for
- * outstanding IOs to complete so that unwritten extent conversion is completed
- * before we try to map the overlapping block. This is currently implemented by
- * hitting it with a big hammer (i.e. inode_dio_wait()).
- *
- * Returns with locks held indicated by @iolock and errors indicated by
- * negative return values.
+ * Handle block aligned direct I/O writes
*/
-STATIC ssize_t
-xfs_file_dio_write(
+static noinline ssize_t
+xfs_file_dio_write_aligned(
+ struct xfs_inode *ip,
struct kiocb *iocb,
struct iov_iter *from)
{
- struct file *file = iocb->ki_filp;
- struct address_space *mapping = file->f_mapping;
- struct inode *inode = mapping->host;
- struct xfs_inode *ip = XFS_I(inode);
- struct xfs_mount *mp = ip->i_mount;
- ssize_t ret = 0;
- int unaligned_io = 0;
- int iolock;
- size_t count = iov_iter_count(from);
- struct xfs_buftarg *target = xfs_inode_buftarg(ip);
+ int iolock = XFS_IOLOCK_SHARED;
+ ssize_t ret;
- /* DIO must be aligned to device logical sector size */
- if ((iocb->ki_pos | count) & target->bt_logical_sectormask)
- return -EINVAL;
+ ret = xfs_ilock_iocb(iocb, iolock);
+ if (ret)
+ return ret;
+ ret = xfs_file_write_checks(iocb, from, &iolock);
+ if (ret)
+ goto out_unlock;
/*
- * Don't take the exclusive iolock here unless the I/O is unaligned to
- * the file system block size. We don't need to consider the EOF
- * extension case here because xfs_file_write_checks() will relock
- * the inode as necessary for EOF zeroing cases and fill out the new
- * inode size as appropriate.
+ * We don't need to hold the IOLOCK exclusively across the IO, so demote
+ * the iolock back to shared if we had to take the exclusive lock in
+ * xfs_file_write_checks() for other reasons.
*/
- if ((iocb->ki_pos & mp->m_blockmask) ||
- ((iocb->ki_pos + count) & mp->m_blockmask)) {
- unaligned_io = 1;
-
- /*
- * We can't properly handle unaligned direct I/O to reflink
- * files yet, as we can't unshare a partial block.
- */
- if (xfs_is_cow_inode(ip)) {
- trace_xfs_reflink_bounce_dio_write(iocb, from);
- return -ENOTBLK;
- }
- iolock = XFS_IOLOCK_EXCL;
- } else {
+ if (iolock == XFS_IOLOCK_EXCL) {
+ xfs_ilock_demote(ip, XFS_IOLOCK_EXCL);
iolock = XFS_IOLOCK_SHARED;
}
+ trace_xfs_file_direct_write(iocb, from);
+ ret = iomap_dio_rw(iocb, from, &xfs_direct_write_iomap_ops,
+ &xfs_dio_write_ops, 0);
+out_unlock:
+ if (iolock)
+ xfs_iunlock(ip, iolock);
+ return ret;
+}
- if (iocb->ki_flags & IOCB_NOWAIT) {
- /* unaligned dio always waits, bail */
- if (unaligned_io)
- return -EAGAIN;
- if (!xfs_ilock_nowait(ip, iolock))
- return -EAGAIN;
- } else {
- xfs_ilock(ip, iolock);
+/*
+ * Handle block unaligned direct I/O writes
+ *
+ * In most cases direct I/O writes will be done holding IOLOCK_SHARED, allowing
+ * them to be done in parallel with reads and other direct I/O writes. However,
+ * if the I/O is not aligned to filesystem blocks, the direct I/O layer may need
+ * to do sub-block zeroing and that requires serialisation against other direct
+ * I/O to the same block. In this case we need to serialise the submission of
+ * the unaligned I/O so that we don't get racing block zeroing in the dio layer.
+ *
+ * This means that unaligned dio writes always block. There is no "nowait" fast
+ * path in this code - if IOCB_NOWAIT is set we simply return -EAGAIN up front
+ * and we don't have to worry about that anymore.
+ */
+static noinline ssize_t
+xfs_file_dio_write_unaligned(
+ struct xfs_inode *ip,
+ struct kiocb *iocb,
+ struct iov_iter *from)
+{
+ int iolock = XFS_IOLOCK_EXCL;
+ ssize_t ret;
+
+ /* unaligned dio always waits, bail */
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EAGAIN;
+ xfs_ilock(ip, iolock);
+
+ /*
+ * We can't properly handle unaligned direct I/O to reflink files yet,
+ * as we can't unshare a partial block.
+ */
+ if (xfs_is_cow_inode(ip)) {
+ trace_xfs_reflink_bounce_dio_write(iocb, from);
+ ret = -ENOTBLK;
+ goto out_unlock;
}
ret = xfs_file_write_checks(iocb, from, &iolock);
if (ret)
- goto out;
- count = iov_iter_count(from);
+ goto out_unlock;
/*
- * If we are doing unaligned IO, we can't allow any other overlapping IO
- * in-flight at the same time or we risk data corruption. Wait for all
- * other IO to drain before we submit. If the IO is aligned, demote the
- * iolock if we had to take the exclusive lock in
- * xfs_file_write_checks() for other reasons.
+ * If we are doing unaligned I/O, this must be the only I/O in-flight.
+ * Otherwise we risk data corruption due to unwritten extent conversions
+ * from the AIO end_io handler. Wait for all other I/O to drain first.
*/
- if (unaligned_io) {
- inode_dio_wait(inode);
- } else if (iolock == XFS_IOLOCK_EXCL) {
- xfs_ilock_demote(ip, XFS_IOLOCK_EXCL);
- iolock = XFS_IOLOCK_SHARED;
- }
+ inode_dio_wait(VFS_I(ip));
trace_xfs_file_direct_write(iocb, from);
- /*
- * If unaligned, this is the only IO in-flight. Wait on it before we
- * release the iolock to prevent subsequent overlapping IO.
- */
ret = iomap_dio_rw(iocb, from, &xfs_direct_write_iomap_ops,
- &xfs_dio_write_ops,
- unaligned_io ? IOMAP_DIO_FORCE_WAIT : 0);
-out:
+ &xfs_dio_write_ops, IOMAP_DIO_FORCE_WAIT);
+out_unlock:
if (iolock)
xfs_iunlock(ip, iolock);
return ret;
}
+static ssize_t
+xfs_file_dio_write(
+ struct kiocb *iocb,
+ struct iov_iter *from)
+{
+ struct xfs_inode *ip = XFS_I(file_inode(iocb->ki_filp));
+ struct xfs_buftarg *target = xfs_inode_buftarg(ip);
+ size_t count = iov_iter_count(from);
+
+ /* direct I/O must be aligned to device logical sector size */
+ if ((iocb->ki_pos | count) & target->bt_logical_sectormask)
+ return -EINVAL;
+ if ((iocb->ki_pos | count) & ip->i_mount->m_blockmask)
+ return xfs_file_dio_write_unaligned(ip, iocb, from);
+ return xfs_file_dio_write_aligned(ip, iocb, from);
+}
+
static noinline ssize_t
xfs_file_dax_write(
struct kiocb *iocb,
projects / linux-2.6-microblaze.git / commitdiff