Fix the way that DAX PMD radix tree entries are handled. With this patch
we now check to see if a PMD entry exists in the radix tree on write, even
if we are just trying to insert a PTE. If it exists, we dirty that instead
of inserting our own PTE entry.
Fix a bug in the PMD path in dax_writeback_mapping_range() where we were
previously passing a loff_t into radix_tree_lookup instead of a pgoff_t.
Account for the fact that multiple fsync/msync operations may be happening
at the same time and don't flush entries that are beyond end_index.
Signed-off-by: Ross Zwisler <ross.zwis...@linux.intel.com>
Reviewed-by: Jan Kara <j...@suse.cz>
---
fs/dax.c | 37 ++++++++++++++++++++++++++-----------
1 file changed, 26 insertions(+), 11 deletions(-)
diff --git a/fs/dax.c b/fs/dax.c
index ab2faa9..a2ed009 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -327,11 +327,13 @@ static int copy_user_bh(struct page *to, struct inode
*inode,
}
#define NO_SECTOR -1
+#define DAX_PMD_INDEX(page_index) (page_index & (PMD_MASK >> PAGE_CACHE_SHIFT))
static int dax_radix_entry(struct address_space *mapping, pgoff_t index,
sector_t sector, bool pmd_entry, bool dirty)
{
struct radix_tree_root *page_tree = &mapping->page_tree;
+ pgoff_t pmd_index = DAX_PMD_INDEX(index);
int type, error = 0;
void *entry;
@@ -339,8 +341,14 @@ static int dax_radix_entry(struct address_space *mapping,
pgoff_t index,
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
spin_lock_irq(&mapping->tree_lock);
- entry = radix_tree_lookup(page_tree, index);
+ entry = radix_tree_lookup(page_tree, pmd_index);
+ if (entry && RADIX_DAX_TYPE(entry) == RADIX_DAX_PMD) {
+ index = pmd_index;
+ goto dirty;
+ }
+
+ entry = radix_tree_lookup(page_tree, index);
if (entry) {
type = RADIX_DAX_TYPE(entry);
if (WARN_ON_ONCE(type != RADIX_DAX_PTE &&
@@ -461,31 +469,33 @@ int dax_writeback_mapping_range(struct address_space
*mapping, loff_t start,
{
struct inode *inode = mapping->host;
struct block_device *bdev = inode->i_sb->s_bdev;
+ pgoff_t start_index, end_index, pmd_index;
pgoff_t indices[PAGEVEC_SIZE];
- pgoff_t start_page, end_page;
struct pagevec pvec;
- void *entry;
+ bool done = false;
int i, ret = 0;
+ void *entry;
if (WARN_ON_ONCE(inode->i_blkbits != PAGE_SHIFT))
return -EIO;
+ start_index = start >> PAGE_CACHE_SHIFT;
+ end_index = end >> PAGE_CACHE_SHIFT;
+ pmd_index = DAX_PMD_INDEX(start_index);
+
rcu_read_lock();
- entry = radix_tree_lookup(&mapping->page_tree, start & PMD_MASK);
+ entry = radix_tree_lookup(&mapping->page_tree, pmd_index);
rcu_read_unlock();
/* see if the start of our range is covered by a PMD entry */
if (entry && RADIX_DAX_TYPE(entry) == RADIX_DAX_PMD)
- start &= PMD_MASK;
-
- start_page = start >> PAGE_CACHE_SHIFT;
- end_page = end >> PAGE_CACHE_SHIFT;
+ start_index = pmd_index;
- tag_pages_for_writeback(mapping, start_page, end_page);
+ tag_pages_for_writeback(mapping, start_index, end_index);
pagevec_init(&pvec, 0);
- while (1) {
- pvec.nr = find_get_entries_tag(mapping, start_page,
+ while (!done) {
+ pvec.nr = find_get_entries_tag(mapping, start_index,
PAGECACHE_TAG_TOWRITE, PAGEVEC_SIZE,
pvec.pages, indices);
@@ -493,6 +503,11 @@ int dax_writeback_mapping_range(struct address_space
*mapping, loff_t start,
break;
for (i = 0; i < pvec.nr; i++) {
+ if (indices[i] > end_index) {
+ done = true;
+ break;
+ }
+
ret = dax_writeback_one(bdev, mapping, indices[i],
pvec.pages[i]);
if (ret < 0)
--
2.5.0
