The patch titled
Subject: dax: never rely on bh.b_dev being set by get_block()
has been added to the -mm tree. Its filename is
dax-never-rely-on-bhb_dev-being-set-by-get_block.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/dax-never-rely-on-bhb_dev-being-set-by-get_block.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/dax-never-rely-on-bhb_dev-being-set-by-get_block.patch
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------------------------------------------------------
From: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Subject: dax: never rely on bh.b_dev being set by get_block()
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>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/dax.c | 3 +++
1 file changed, 3 insertions(+)
diff -puN fs/dax.c~dax-never-rely-on-bhb_dev-being-set-by-get_block fs/dax.c
--- a/fs/dax.c~dax-never-rely-on-bhb_dev-being-set-by-get_block
+++ a/fs/dax.c
@@ -246,6 +246,7 @@ ssize_t dax_do_io(struct kiocb *iocb, st
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;
@@ -606,6 +607,7 @@ int __dax_fault(struct vm_area_struct *v
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:
@@ -1077,6 +1079,7 @@ int dax_zero_page_range(struct inode *in
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)
_
Patches currently in -mm which might be from ross.zwisler@xxxxxxxxxxxxxxx are
dax-fix-null-pointer-dereference-in-__dax_dbg.patch
dax-fix-conversion-of-holes-to-pmds.patch
pmem-add-wb_cache_pmem-to-the-pmem-api.patch
pmem-add-wb_cache_pmem-to-the-pmem-api-v6.patch
dax-support-dirty-dax-entries-in-radix-tree.patch
dax-support-dirty-dax-entries-in-radix-tree-v6.patch
mm-add-find_get_entries_tag.patch
dax-add-support-for-fsync-sync.patch
dax-add-support-for-fsync-sync-v6.patch
dax-add-support-for-fsync-msync-v7.patch
dax-add-support-for-fsync-msync-v8.patch
dax-add-support-for-fsync-msync-v8-fix.patch
dax-add-support-for-fsync-msync-v8-fix-2.patch
dax-add-support-for-fsync-msync-v8-fix-3.patch
dax-add-support-for-fsync-sync-v8-fix-4.patch
ext2-call-dax_pfn_mkwrite-for-dax-fsync-msync.patch
ext4-call-dax_pfn_mkwrite-for-dax-fsync-msync.patch
xfs-call-dax_pfn_mkwrite-for-dax-fsync-msync.patch
dax-never-rely-on-bhb_dev-being-set-by-get_block.patch
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