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 <[email protected]> --- fs/dax.c | 39 +++++++++++++++++++++++++++------------ 1 file changed, 27 insertions(+), 12 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index 55ae394..afacc30 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -327,19 +327,27 @@ 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; __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 (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 && @@ -460,31 +468,33 @@ 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; + if (RADIX_DAX_TYPE(entry) == RADIX_DAX_PMD) + 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); @@ -492,6 +502,11 @@ 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
