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authorDan Williams <dan.j.williams@intel.com>2018-07-13 21:50:16 -0700
committerDave Jiang <dave.jiang@intel.com>2018-07-23 10:38:06 -0700
commitc2a7d2a115525d3501d38e23d24875a79a07e15e (patch)
treedf178de827dbda4bce219d4bfb812581d4883b53 /include
parentae1139ece126b8eb6d0770094fbac43ea928d9d9 (diff)
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filesystem-dax: Introduce dax_lock_mapping_entry()
In preparation for implementing support for memory poison (media error) handling via dax mappings, implement a lock_page() equivalent. Poison error handling requires rmap and needs guarantees that the page->mapping association is maintained / valid (inode not freed) for the duration of the lookup. In the device-dax case it is sufficient to simply hold a dev_pagemap reference. In the filesystem-dax case we need to use the entry lock. Export the entry lock via dax_lock_mapping_entry() that uses rcu_read_lock() to protect against the inode being freed, and revalidates the page->mapping association under xa_lock(). Cc: Christoph Hellwig <hch@lst.de> Cc: Matthew Wilcox <willy@infradead.org> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Diffstat (limited to 'include')
-rw-r--r--include/linux/dax.h13
1 files changed, 13 insertions, 0 deletions
diff --git a/include/linux/dax.h b/include/linux/dax.h
index deb0f663252f..450b28db9533 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -88,6 +88,8 @@ int dax_writeback_mapping_range(struct address_space *mapping,
struct block_device *bdev, struct writeback_control *wbc);
struct page *dax_layout_busy_page(struct address_space *mapping);
+bool dax_lock_mapping_entry(struct page *page);
+void dax_unlock_mapping_entry(struct page *page);
#else
static inline bool bdev_dax_supported(struct block_device *bdev,
int blocksize)
@@ -119,6 +121,17 @@ static inline int dax_writeback_mapping_range(struct address_space *mapping,
{
return -EOPNOTSUPP;
}
+
+static inline bool dax_lock_mapping_entry(struct page *page)
+{
+ if (IS_DAX(page->mapping->host))
+ return true;
+ return false;
+}
+
+static inline void dax_unlock_mapping_entry(struct page *page)
+{
+}
#endif
int dax_read_lock(void);