From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Some filesystems want to be able to limit the maximum size of folios,
and some want to be able to ensure that folios are at least a certain
size. Add mapping_set_folio_orders() to allow this level of control
(although it is not yet honoured).
[Pankaj]: added mapping_min_folio_order()
Signed-off-by: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
---
include/linux/pagemap.h | 48 ++++++++++++++++++++++++++++++++++++-----
1 file changed, 43 insertions(+), 5 deletions(-)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 351c3b7f93a1..129d62a891be 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -202,10 +202,16 @@ enum mapping_flags {
AS_EXITING = 4, /* final truncate in progress */
/* writeback related tags are not used */
AS_NO_WRITEBACK_TAGS = 5,
- AS_LARGE_FOLIO_SUPPORT = 6,
- AS_RELEASE_ALWAYS, /* Call ->release_folio(), even if no private data */
+ AS_RELEASE_ALWAYS = 6, /* Call ->release_folio(), even if no private data */
+ AS_FOLIO_ORDER_MIN = 8,
+ AS_FOLIO_ORDER_MAX = 13,
+ /* 8-17 are used for FOLIO_ORDER */
};
+#define AS_FOLIO_ORDER_MIN_MASK 0x00001f00
+#define AS_FOLIO_ORDER_MAX_MASK 0x0002e000
+#define AS_FOLIO_ORDER_MASK (AS_FOLIO_ORDER_MIN_MASK | AS_FOLIO_ORDER_MAX_MASK)
+
/**
* mapping_set_error - record a writeback error in the address_space
* @mapping: the mapping in which an error should be set
@@ -310,6 +316,29 @@ static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
m->gfp_mask = mask;
}
+/**
+ * mapping_set_folio_orders() - Set the range of folio sizes supported.
+ * @mapping: The file.
+ * @min: Minimum folio order (between 0-31 inclusive).
+ * @max: Maximum folio order (between 0-31 inclusive).
+ *
+ * The filesystem should call this function in its inode constructor to
+ * indicate which sizes of folio the VFS can use to cache the contents
+ * of the file. This should only be used if the filesystem needs special
+ * handling of folio sizes (ie there is something the core cannot know).
+ * Do not tune it based on, eg, i_size.
+ *
+ * Context: This should not be called while the inode is active as it
+ * is non-atomic.
+ */
+static inline void mapping_set_folio_orders(struct address_space *mapping,
+ unsigned int min, unsigned int max)
+{
+ mapping->flags = (mapping->flags & ~AS_FOLIO_ORDER_MASK) |
+ (min << AS_FOLIO_ORDER_MIN) |
+ (max << AS_FOLIO_ORDER_MAX);
+}
+
/**
* mapping_set_large_folios() - Indicate the file supports large folios.
* @mapping: The file.
@@ -323,7 +352,17 @@ static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
*/
static inline void mapping_set_large_folios(struct address_space *mapping)
{
- __set_bit(AS_LARGE_FOLIO_SUPPORT, &mapping->flags);
+ mapping_set_folio_orders(mapping, 0, 31);
+}
+
+static inline unsigned mapping_max_folio_order(struct address_space *mapping)
+{
+ return (mapping->flags & AS_FOLIO_ORDER_MAX_MASK) >> AS_FOLIO_ORDER_MAX;
+}
+
+static inline unsigned mapping_min_folio_order(struct address_space *mapping)
+{
+ return (mapping->flags & AS_FOLIO_ORDER_MIN_MASK) >> AS_FOLIO_ORDER_MIN;
}
/*
@@ -332,8 +371,7 @@ static inline void mapping_set_large_folios(struct address_space *mapping)
*/
static inline bool mapping_large_folio_support(struct address_space *mapping)
{
- return IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
- test_bit(AS_LARGE_FOLIO_SUPPORT, &mapping->flags);
+ return mapping_max_folio_order(mapping) > 0;
}
static inline int filemap_nr_thps(struct address_space *mapping)
--
2.35.3
