dax_do_io (called for read() or write() for a dax file system) may fail
in the presence of bad blocks or media errors. Since we expect that a
write should clear media errors on nvdimms, make dax_do_io fall back to
the direct_IO path, which will send down a bio to the driver, which can
then attempt to clear the error.

Cc: Matthew Wilcox <matthew.r.wil...@intel.com>
Cc: Dan Williams <dan.j.willi...@intel.com>
Cc: Ross Zwisler <ross.zwis...@linux.intel.com>
Cc: Dave Chinner <da...@fromorbit.com>
Cc: Jan Kara <j...@suse.cz>
Cc: Jens Axboe <ax...@fb.com>
Cc: Al Viro <v...@zeniv.linux.org.uk>
Cc: Christoph Hellwig <h...@infradead.org>
Signed-off-by: Vishal Verma <vishal.l.ve...@intel.com>
---
 fs/block_dev.c     | 17 ++++++++++++++---
 fs/ext2/inode.c    | 22 +++++++++++++++-------
 fs/ext4/indirect.c | 18 +++++++++++++-----
 fs/ext4/inode.c    | 21 ++++++++++++++-------
 fs/xfs/xfs_aops.c  | 14 ++++++++++++--
 5 files changed, 68 insertions(+), 24 deletions(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index c5837fa..d6113b9 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -166,13 +166,24 @@ blkdev_direct_IO(struct kiocb *iocb, struct iov_iter 
*iter, loff_t offset)
 {
        struct file *file = iocb->ki_filp;
        struct inode *inode = bdev_file_inode(file);
+       ssize_t ret, ret_saved = 0;
 
-       if (IS_DAX(inode))
-               return dax_do_io(iocb, inode, iter, offset, blkdev_get_block,
+       if (IS_DAX(inode)) {
+               ret = dax_do_io(iocb, inode, iter, offset, blkdev_get_block,
                                NULL, DIO_SKIP_DIO_COUNT);
-       return __blockdev_direct_IO(iocb, inode, I_BDEV(inode), iter, offset,
+               if (ret == -EIO && (iov_iter_rw(iter) == WRITE))
+                       ret_saved = ret;
+               else
+                       return ret;
+       }
+
+       ret = __blockdev_direct_IO(iocb, inode, I_BDEV(inode), iter, offset,
                                    blkdev_get_block, NULL, NULL,
                                    DIO_SKIP_DIO_COUNT);
+       if (ret < 0 && ret_saved)
+               return ret_saved;
+
+       return ret;
 }
 
 int __sync_blockdev(struct block_device *bdev, int wait)
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 824f249..64792c6 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -859,14 +859,22 @@ ext2_direct_IO(struct kiocb *iocb, struct iov_iter *iter, 
loff_t offset)
        struct address_space *mapping = file->f_mapping;
        struct inode *inode = mapping->host;
        size_t count = iov_iter_count(iter);
-       ssize_t ret;
+       ssize_t ret, ret_saved = 0;
 
-       if (IS_DAX(inode))
-               ret = dax_do_io(iocb, inode, iter, offset, ext2_get_block, NULL,
-                               DIO_LOCKING);
-       else
-               ret = blockdev_direct_IO(iocb, inode, iter, offset,
-                                        ext2_get_block);
+       if (IS_DAX(inode)) {
+               ret = dax_do_io(iocb, inode, iter, offset, ext2_get_block,
+                               NULL, DIO_LOCKING | DIO_SKIP_HOLES);
+               if (ret == -EIO && iov_iter_rw(iter) == WRITE)
+                       ret_saved = ret;
+               else
+                       goto out;
+       }
+
+       ret = blockdev_direct_IO(iocb, inode, iter, offset, ext2_get_block);
+       if (ret < 0 && ret_saved)
+               ret = ret_saved;
+
+ out:
        if (ret < 0 && iov_iter_rw(iter) == WRITE)
                ext2_write_failed(mapping, offset + count);
        return ret;
diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
index 3027fa6..798f341 100644
--- a/fs/ext4/indirect.c
+++ b/fs/ext4/indirect.c
@@ -716,14 +716,22 @@ retry:
                                                   NULL, NULL, 0);
                inode_dio_end(inode);
        } else {
+               ssize_t ret_saved = 0;
+
 locked:
-               if (IS_DAX(inode))
+               if (IS_DAX(inode)) {
                        ret = dax_do_io(iocb, inode, iter, offset,
                                        ext4_dio_get_block, NULL, DIO_LOCKING);
-               else
-                       ret = blockdev_direct_IO(iocb, inode, iter, offset,
-                                                ext4_dio_get_block);
-
+                       if (ret == -EIO && iov_iter_rw(iter) == WRITE)
+                               ret_saved = ret;
+                       else
+                               goto skip_dio;
+               }
+               ret = blockdev_direct_IO(iocb, inode, iter, offset,
+                                        ext4_get_block);
+               if (ret < 0 && ret_saved)
+                       ret = ret_saved;
+skip_dio:
                if (unlikely(iov_iter_rw(iter) == WRITE && ret < 0)) {
                        loff_t isize = i_size_read(inode);
                        loff_t end = offset + count;
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index dab84a2..27f07c2 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3341,7 +3341,7 @@ static ssize_t ext4_ext_direct_IO(struct kiocb *iocb, 
struct iov_iter *iter,
 {
        struct file *file = iocb->ki_filp;
        struct inode *inode = file->f_mapping->host;
-       ssize_t ret;
+       ssize_t ret, ret_saved = 0;
        size_t count = iov_iter_count(iter);
        int overwrite = 0;
        get_block_t *get_block_func = NULL;
@@ -3401,15 +3401,22 @@ static ssize_t ext4_ext_direct_IO(struct kiocb *iocb, 
struct iov_iter *iter,
 #ifdef CONFIG_EXT4_FS_ENCRYPTION
        BUG_ON(ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode));
 #endif
-       if (IS_DAX(inode))
+       if (IS_DAX(inode)) {
                ret = dax_do_io(iocb, inode, iter, offset, get_block_func,
                                ext4_end_io_dio, dio_flags);
-       else
-               ret = __blockdev_direct_IO(iocb, inode,
-                                          inode->i_sb->s_bdev, iter, offset,
-                                          get_block_func,
-                                          ext4_end_io_dio, NULL, dio_flags);
+               if (ret == -EIO && iov_iter_rw(iter) == WRITE)
+                       ret_saved = ret;
+               else
+                       goto skip_dio;
+       }
 
+       ret = __blockdev_direct_IO(iocb, inode,
+                                  inode->i_sb->s_bdev, iter, offset,
+                                  get_block_func,
+                                  ext4_end_io_dio, NULL, dio_flags);
+       if (ret < 0 && ret_saved)
+               ret = ret_saved;
+ skip_dio:
        if (ret > 0 && !overwrite && ext4_test_inode_state(inode,
                                                EXT4_STATE_DIO_UNWRITTEN)) {
                int err;
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index d445a64..7cfcf86 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -1413,6 +1413,7 @@ xfs_vm_direct_IO(
        dio_iodone_t            *endio = NULL;
        int                     flags = 0;
        struct block_device     *bdev;
+       ssize_t                 ret, ret_saved = 0;
 
        if (iov_iter_rw(iter) == WRITE) {
                endio = xfs_end_io_direct_write;
@@ -1420,13 +1421,22 @@ xfs_vm_direct_IO(
        }
 
        if (IS_DAX(inode)) {
-               return dax_do_io(iocb, inode, iter, offset,
+               ret = dax_do_io(iocb, inode, iter, offset,
                                 xfs_get_blocks_direct, endio, 0);
+               if (ret == -EIO && iov_iter_rw(iter) == WRITE)
+                       ret_saved = ret;
+               else
+                       return ret;
        }
 
        bdev = xfs_find_bdev_for_inode(inode);
-       return  __blockdev_direct_IO(iocb, inode, bdev, iter, offset,
+       ret = __blockdev_direct_IO(iocb, inode, bdev, iter, offset,
                        xfs_get_blocks_direct, endio, NULL, flags);
+
+       if (ret < 0 && ret_saved)
+               ret = ret_saved;
+
+       return ret;
 }
 
 /*
-- 
2.5.5

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