Previously in DAX we assumed that calls to get_block() would set bh.b_bdev,
and we would then use that value even in error cases for debugging. This
caused a NULL pointer dereference in __dax_dbg() which was fixed by a
previous commit, but that commit only changed the one place where we were
hitting an error.
Instead, update dax.c so that we always initialize bh.b_bdev as best we can
based on the information that DAX has. get_block() may or may not update
to a new value, but this at least lets us get something helpful from
bh.b_bdev for error messages and not have to worry about whether it was set
by get_block() or not.
Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Reported-by: Jan Kara <jack@xxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
---
fs/dax.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/fs/dax.c b/fs/dax.c
index 0db21ea..cee9e1b 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -246,6 +246,7 @@ ssize_t dax_do_io(struct kiocb *iocb, struct inode *inode,
loff_t end = pos + iov_iter_count(iter);
memset(&bh, 0, sizeof(bh));
+ bh.b_bdev = inode->i_sb->s_bdev;
if ((flags & DIO_LOCKING) && iov_iter_rw(iter) == READ) {
struct address_space *mapping = inode->i_mapping;
@@ -582,6 +583,7 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
memset(&bh, 0, sizeof(bh));
block = (sector_t)vmf->pgoff << (PAGE_SHIFT - blkbits);
+ bh.b_bdev = inode->i_sb->s_bdev;
bh.b_size = PAGE_SIZE;
repeat:
@@ -1018,6 +1020,7 @@ int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length,
BUG_ON((offset + length) > PAGE_CACHE_SIZE);
memset(&bh, 0, sizeof(bh));
+ bh.b_bdev = inode->i_sb->s_bdev;
bh.b_size = PAGE_CACHE_SIZE;
err = get_block(inode, index, &bh, 0);
if (err < 0)
--
2.5.0
--
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