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authorShiyang Ruan <ruansy.fnst@fujitsu.com>2022-06-03 13:37:28 +0800
committerakpm <akpm@linux-foundation.org>2022-07-17 17:14:30 -0700
commit2f437effc689ef913fbe5e31110580b4e7cf04be (patch)
treef27e3698252a5f32a512afd27bc6bee0c34e55fd /fs
parent33a8f7f2b3a3437d016d1b4047a4fd37eb6951b3 (diff)
fsdax: introduce dax_lock_mapping_entry()
The current dax_lock_page() locks dax entry by obtaining mapping and index in page. To support 1-to-N RMAP in NVDIMM, we need a new function to lock a specific dax entry corresponding to this file's mapping,index. And output the page corresponding to the specific dax entry for caller use. Link: https://lkml.kernel.org/r/20220603053738.1218681-5-ruansy.fnst@fujitsu.com Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Dan Williams <dan.j.wiliams@intel.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Goldwyn Rodrigues <rgoldwyn@suse.com> Cc: Goldwyn Rodrigues <rgoldwyn@suse.de> Cc: Jane Chu <jane.chu@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Ritesh Harjani <riteshh@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/dax.c63
1 files changed, 63 insertions, 0 deletions
diff --git a/fs/dax.c b/fs/dax.c
index 4155a6107fa1..65e44d78b3bb 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -456,6 +456,69 @@ void dax_unlock_page(struct page *page, dax_entry_t cookie)
}
/*
+ * dax_lock_mapping_entry - Lock the DAX entry corresponding to a mapping
+ * @mapping: the file's mapping whose entry we want to lock
+ * @index: the offset within this file
+ * @page: output the dax page corresponding to this dax entry
+ *
+ * Return: A cookie to pass to dax_unlock_mapping_entry() or 0 if the entry
+ * could not be locked.
+ */
+dax_entry_t dax_lock_mapping_entry(struct address_space *mapping, pgoff_t index,
+ struct page **page)
+{
+ XA_STATE(xas, NULL, 0);
+ void *entry;
+
+ rcu_read_lock();
+ for (;;) {
+ entry = NULL;
+ if (!dax_mapping(mapping))
+ break;
+
+ xas.xa = &mapping->i_pages;
+ xas_lock_irq(&xas);
+ xas_set(&xas, index);
+ entry = xas_load(&xas);
+ if (dax_is_locked(entry)) {
+ rcu_read_unlock();
+ wait_entry_unlocked(&xas, entry);
+ rcu_read_lock();
+ continue;
+ }
+ if (!entry ||
+ dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) {
+ /*
+ * Because we are looking for entry from file's mapping
+ * and index, so the entry may not be inserted for now,
+ * or even a zero/empty entry. We don't think this is
+ * an error case. So, return a special value and do
+ * not output @page.
+ */
+ entry = (void *)~0UL;
+ } else {
+ *page = pfn_to_page(dax_to_pfn(entry));
+ dax_lock_entry(&xas, entry);
+ }
+ xas_unlock_irq(&xas);
+ break;
+ }
+ rcu_read_unlock();
+ return (dax_entry_t)entry;
+}
+
+void dax_unlock_mapping_entry(struct address_space *mapping, pgoff_t index,
+ dax_entry_t cookie)
+{
+ XA_STATE(xas, &mapping->i_pages, index);
+
+ if (cookie == ~0UL)
+ return;
+
+ dax_unlock_entry(&xas, (void *)cookie);
+}
+
+/*
* Find page cache entry at given index. If it is a DAX entry, return it
* with the entry locked. If the page cache doesn't contain an entry at
* that index, add a locked empty entry.