xfs: new truncate sequence

Convert XFS to the new truncate sequence.  We still can have errors after
updating the file size in xfs_setattr, but these are real I/O errors and lead
to a transaction abort and filesystem shutdown, so they are not an issue.

Errors from ->write_begin and write_end can now be handled correctly because
we can actually get rid of the delalloc extents while previous the buffer
state was stipped in block_invalidatepage.

There is still no error handling for ->direct_IO, because doing so will need
some major restructuring given that we only have the iolock shared and do not
hold i_mutex at all.  Fortunately leaving the normally allocated blocks behind
there is not a major issue and this will get cleaned up by xfs_free_eofblock
later.

Note: the patch is against Al's vfs.git tree as that contains the nessecary
preparations.  I'd prefer to get it applied there so that we can get some
testing in linux-next.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 20 insertions, 18 deletions

diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c
index 3ac137dd531b..66d585c6917c 100644
--- a/fs/xfs/xfs_vnodeops.c
+++ b/fs/xfs/xfs_vnodeops.c
@@ -221,8 +221,11 @@ xfs_setattr(
                          * transaction to modify the i_size.
                          */
                         code = xfs_zero_eof(ip, iattr->ia_size, ip->i_size);
+                        if (code)
+                                goto error_return;
                 }
                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
+                lock_flags &= ~XFS_ILOCK_EXCL;
 
                 /*
                  * We are going to log the inode size change in this
@@ -236,36 +239,35 @@ xfs_setattr(
                  * really care about here and prevents waiting for other data
                  * not within the range we care about here.
                  */
-                if (!code &&
-                    ip->i_size != ip->i_d.di_size &&
+                if (ip->i_size != ip->i_d.di_size &&
                     iattr->ia_size > ip->i_d.di_size) {
                         code = xfs_flush_pages(ip,
                                         ip->i_d.di_size, iattr->ia_size,
                                         XBF_ASYNC, FI_NONE);
+                        if (code)
+                                goto error_return;
                 }
 
                 /* wait for all I/O to complete */
                 xfs_ioend_wait(ip);
 
-                if (!code)
-                        code = xfs_itruncate_data(ip, iattr->ia_size);
-                if (code) {
-                        ASSERT(tp == NULL);
-                        lock_flags &= ~XFS_ILOCK_EXCL;
-                        ASSERT(lock_flags == XFS_IOLOCK_EXCL || !need_iolock);
+                code = -block_truncate_page(inode->i_mapping, iattr->ia_size,
+                                            xfs_get_blocks);
+                if (code)
                         goto error_return;
-                }
+
                 tp = xfs_trans_alloc(mp, XFS_TRANS_SETATTR_SIZE);
-                if ((code = xfs_trans_reserve(tp, 0,
-                                             XFS_ITRUNCATE_LOG_RES(mp), 0,
-                                             XFS_TRANS_PERM_LOG_RES,
-                                             XFS_ITRUNCATE_LOG_COUNT))) {
-                        xfs_trans_cancel(tp, 0);
-                        if (need_iolock)
-                                xfs_iunlock(ip, XFS_IOLOCK_EXCL);
-                        return code;
-                }
+                code = xfs_trans_reserve(tp, 0, XFS_ITRUNCATE_LOG_RES(mp), 0,
+                                         XFS_TRANS_PERM_LOG_RES,
+                                         XFS_ITRUNCATE_LOG_COUNT);
+                if (code)
+                        goto error_return;
+
+                truncate_setsize(inode, iattr->ia_size);
+
                 commit_flags = XFS_TRANS_RELEASE_LOG_RES;
+                lock_flags |= XFS_ILOCK_EXCL;
+
                 xfs_ilock(ip, XFS_ILOCK_EXCL);
 
                 xfs_trans_ijoin(tp, ip);