Sync syscall to DAX file needs to flush processor cache, but it currently does not flush to existing DAX files. This is because 'ext4_da_aops' is set to address_space_operations of existing DAX files, instead of 'ext4_dax_aops', since S_DAX flag is set after ext4_set_aops() in the open path.

New file -------- lookup_open ext4_create __ext4_new_inode ext4_set_inode_flags // Set S_DAX flag ext4_set_aops // Set aops to ext4_dax_aops

Existing file ------------- lookup_open ext4_lookup ext4_iget ext4_set_aops // Set aops to ext4_da_aops ext4_set_inode_flags // Set S_DAX flag

Change ext4_iget() to initialize i_flags before ext4_set_aops().

Fixes: 5f0663bb4a64 ("ext4, dax: introduce ext4_dax_aops") Signed-off-by: Toshi Kani toshi.kani@hpe.com Suggested-by: Jan Kara jack@suse.cz Cc: Jan Kara jack@suse.cz Cc: Dan Williams dan.j.williams@intel.com Cc: "Theodore Ts'o" tytso@mit.edu Cc: Andreas Dilger adilger.kernel@dilger.ca Cc: stable@vger.kernel.org --- fs/ext4/inode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index e4acaa980467..b19387b75f2b 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4896,6 +4896,7 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino) * not initialized on a new filesystem. */ } ei->i_flags = le32_to_cpu(raw_inode->i_flags); + ext4_set_inode_flags(inode); inode->i_blocks = ext4_inode_blocks(raw_inode, ei); ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl_lo); if (ext4_has_feature_64bit(sb)) @@ -5042,7 +5043,6 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino) goto bad_inode; } brelse(iloc.bh); - ext4_set_inode_flags(inode);

unlock_new_inode(inode); return inode;