On Tue 16-02-16 20:34:15, Ross Zwisler wrote: > When S_DAX is set on an inode we assume that if there are pages attached > to the mapping (mapping->nrpages != 0), those pages are clean zero pages > that were used to service reads from holes. Any dirty data associated with > the inode should be in the form of DAX exceptional entries > (mapping->nrexceptional) that is written back via > dax_writeback_mapping_range(). > > With the current code, though, this isn't always true. For example, ext2 > and ext4 directory inodes can have S_DAX set, but have their dirty data > stored as dirty page cache entries. For these types of inodes, having > S_DAX set doesn't really make sense since their I/O doesn't actually happen > through the DAX code path. > > Instead, only allow S_DAX to be set for regular inodes for ext2 and ext4. > This allows us to have strict DAX vs non-DAX paths in the writeback code. > > Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx> Looks good. You can add: Reviewed-by: Jan Kara <jack@xxxxxxx> Honza > --- > fs/ext2/inode.c | 2 +- > fs/ext4/inode.c | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c > index 338eefd..27e2cdd 100644 > --- a/fs/ext2/inode.c > +++ b/fs/ext2/inode.c > @@ -1296,7 +1296,7 @@ void ext2_set_inode_flags(struct inode *inode) > inode->i_flags |= S_NOATIME; > if (flags & EXT2_DIRSYNC_FL) > inode->i_flags |= S_DIRSYNC; > - if (test_opt(inode->i_sb, DAX)) > + if (test_opt(inode->i_sb, DAX) && S_ISREG(inode->i_mode)) > inode->i_flags |= S_DAX; > } > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 83bc8bf..7088aa5 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -4127,7 +4127,7 @@ void ext4_set_inode_flags(struct inode *inode) > new_fl |= S_NOATIME; > if (flags & EXT4_DIRSYNC_FL) > new_fl |= S_DIRSYNC; > - if (test_opt(inode->i_sb, DAX)) > + if (test_opt(inode->i_sb, DAX) && S_ISREG(inode->i_mode)) > new_fl |= S_DAX; > inode_set_flags(inode, new_fl, > S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC|S_DAX); > -- > 2.5.0 > > -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>