| Message ID | 1461015341-20153-16-git-send-email-jack@suse.cz (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
On Mon, Apr 18, 2016 at 11:35:38PM +0200, Jan Kara wrote: > Currently we forbid page_cache_tree_insert() to replace exceptional radix > tree entries for DAX inodes. However to make DAX faults race free we will > lock radix tree entries and when hole is created, we need to replace > such locked radix tree entry with a hole page. So modify > page_cache_tree_insert() to allow that. > > Signed-off-by: Jan Kara <jack@suse.cz> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
diff --git a/include/linux/dax.h b/include/linux/dax.h index bef5c44f71b3..fd4aeae65ed7 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -3,6 +3,7 @@ #include <linux/fs.h> #include <linux/mm.h> +#include <linux/radix-tree.h> #include <asm/pgtable.h> /* We use lowest available exceptional entry bit for locking */ diff --git a/mm/filemap.c b/mm/filemap.c index f2479af09da9..3effd5c8f2f6 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -597,14 +597,18 @@ static int page_cache_tree_insert(struct address_space *mapping, if (!radix_tree_exceptional_entry(p)) return -EEXIST; - if (WARN_ON(dax_mapping(mapping))) - return -EINVAL; - - if (shadowp) - *shadowp = p; mapping->nrexceptional--; - if (node) - workingset_node_shadows_dec(node); + if (!dax_mapping(mapping)) { + if (shadowp) + *shadowp = p; + if (node) + workingset_node_shadows_dec(node); + } else { + /* DAX can replace empty locked entry with a hole */ + WARN_ON_ONCE(p != + (void *)(RADIX_TREE_EXCEPTIONAL_ENTRY | + RADIX_DAX_ENTRY_LOCK)); + } } radix_tree_replace_slot(slot, page); mapping->nrpages++;
Currently we forbid page_cache_tree_insert() to replace exceptional radix tree entries for DAX inodes. However to make DAX faults race free we will lock radix tree entries and when hole is created, we need to replace such locked radix tree entry with a hole page. So modify page_cache_tree_insert() to allow that. Signed-off-by: Jan Kara <jack@suse.cz> --- include/linux/dax.h | 1 + mm/filemap.c | 18 +++++++++++------- 2 files changed, 12 insertions(+), 7 deletions(-)