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-rw-r--r--mm/shmem.c50
1 files changed, 26 insertions, 24 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index 54bec60380df..ceba031d9985 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2620,12 +2620,13 @@ static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
/*
* We need a tag: a new tag would expand every radix_tree_node by 8 bytes,
- * so reuse a tag which we firmly believe is never set or cleared on shmem.
+ * so reuse a tag which we firmly believe is never set or cleared on tmpfs
+ * or hugetlbfs because they are memory only filesystems.
*/
-#define SHMEM_TAG_PINNED PAGECACHE_TAG_TOWRITE
+#define MEMFD_TAG_PINNED PAGECACHE_TAG_TOWRITE
#define LAST_SCAN 4 /* about 150ms max */
-static void shmem_tag_pins(struct address_space *mapping)
+static void memfd_tag_pins(struct address_space *mapping)
{
struct radix_tree_iter iter;
void __rcu **slot;
@@ -2646,7 +2647,7 @@ static void shmem_tag_pins(struct address_space *mapping)
} else if (page_count(page) - page_mapcount(page) > 1) {
xa_lock_irq(&mapping->i_pages);
radix_tree_tag_set(&mapping->i_pages, iter.index,
- SHMEM_TAG_PINNED);
+ MEMFD_TAG_PINNED);
xa_unlock_irq(&mapping->i_pages);
}
@@ -2667,7 +2668,7 @@ static void shmem_tag_pins(struct address_space *mapping)
* The caller must guarantee that no new user will acquire writable references
* to those pages to avoid races.
*/
-static int shmem_wait_for_pins(struct address_space *mapping)
+static int memfd_wait_for_pins(struct address_space *mapping)
{
struct radix_tree_iter iter;
void __rcu **slot;
@@ -2675,11 +2676,11 @@ static int shmem_wait_for_pins(struct address_space *mapping)
struct page *page;
int error, scan;
- shmem_tag_pins(mapping);
+ memfd_tag_pins(mapping);
error = 0;
for (scan = 0; scan <= LAST_SCAN; scan++) {
- if (!radix_tree_tagged(&mapping->i_pages, SHMEM_TAG_PINNED))
+ if (!radix_tree_tagged(&mapping->i_pages, MEMFD_TAG_PINNED))
break;
if (!scan)
@@ -2690,7 +2691,7 @@ static int shmem_wait_for_pins(struct address_space *mapping)
start = 0;
rcu_read_lock();
radix_tree_for_each_tagged(slot, &mapping->i_pages, &iter,
- start, SHMEM_TAG_PINNED) {
+ start, MEMFD_TAG_PINNED) {
page = radix_tree_deref_slot(slot);
if (radix_tree_exception(page)) {
@@ -2717,7 +2718,7 @@ static int shmem_wait_for_pins(struct address_space *mapping)
xa_lock_irq(&mapping->i_pages);
radix_tree_tag_clear(&mapping->i_pages,
- iter.index, SHMEM_TAG_PINNED);
+ iter.index, MEMFD_TAG_PINNED);
xa_unlock_irq(&mapping->i_pages);
continue_resched:
if (need_resched()) {
@@ -2733,11 +2734,11 @@ continue_resched:
static unsigned int *memfd_file_seals_ptr(struct file *file)
{
- if (file->f_op == &shmem_file_operations)
+ if (shmem_file(file))
return &SHMEM_I(file_inode(file))->seals;
#ifdef CONFIG_HUGETLBFS
- if (file->f_op == &hugetlbfs_file_operations)
+ if (is_file_hugepages(file))
return &HUGETLBFS_I(file_inode(file))->seals;
#endif
@@ -2757,16 +2758,17 @@ static int memfd_add_seals(struct file *file, unsigned int seals)
/*
* SEALING
- * Sealing allows multiple parties to share a shmem-file but restrict
- * access to a specific subset of file operations. Seals can only be
- * added, but never removed. This way, mutually untrusted parties can
- * share common memory regions with a well-defined policy. A malicious
- * peer can thus never perform unwanted operations on a shared object.
+ * Sealing allows multiple parties to share a tmpfs or hugetlbfs file
+ * but restrict access to a specific subset of file operations. Seals
+ * can only be added, but never removed. This way, mutually untrusted
+ * parties can share common memory regions with a well-defined policy.
+ * A malicious peer can thus never perform unwanted operations on a
+ * shared object.
*
- * Seals are only supported on special shmem-files and always affect
- * the whole underlying inode. Once a seal is set, it may prevent some
- * kinds of access to the file. Currently, the following seals are
- * defined:
+ * Seals are only supported on special tmpfs or hugetlbfs files and
+ * always affect the whole underlying inode. Once a seal is set, it
+ * may prevent some kinds of access to the file. Currently, the
+ * following seals are defined:
* SEAL_SEAL: Prevent further seals from being set on this file
* SEAL_SHRINK: Prevent the file from shrinking
* SEAL_GROW: Prevent the file from growing
@@ -2780,9 +2782,9 @@ static int memfd_add_seals(struct file *file, unsigned int seals)
* added.
*
* Semantics of sealing are only defined on volatile files. Only
- * anonymous shmem files support sealing. More importantly, seals are
- * never written to disk. Therefore, there's no plan to support it on
- * other file types.
+ * anonymous tmpfs and hugetlbfs files support sealing. More
+ * importantly, seals are never written to disk. Therefore, there's
+ * no plan to support it on other file types.
*/
if (!(file->f_mode & FMODE_WRITE))
@@ -2808,7 +2810,7 @@ static int memfd_add_seals(struct file *file, unsigned int seals)
if (error)
goto unlock;
- error = shmem_wait_for_pins(file->f_mapping);
+ error = memfd_wait_for_pins(file->f_mapping);
if (error) {
mapping_allow_writable(file->f_mapping);
goto unlock;