On 5/27/24 23:01, Matthew Wilcox (Oracle) wrote:
We need filesystems to be able to communicate acceptable folio sizes
to the pagecache for a variety of uses (e.g. large block sizes).
Support a range of folio sizes between order-0 and order-31.
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Co-developed-by: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
Signed-off-by: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
---
For this version, I fixed the TODO that the maximum folio size was not
being honoured. I made some other changes too like adding const, moving
the location of the constants, checking CONFIG_TRANSPARENT_HUGEPAGE, and
dropping some of the functions which aren't needed until later patches.
(They can be added in the commits that need them). Also rebased against
current Linus tree, so MAX_PAGECACHE_ORDER no longer needs to be moved).
include/linux/pagemap.h | 81 +++++++++++++++++++++++++++++++++++------
mm/filemap.c | 6 +--
mm/readahead.c | 4 +-
3 files changed, 73 insertions(+), 18 deletions(-)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 1ed9274a0deb..c6aaceed0de6 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -204,13 +204,18 @@ 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_STABLE_WRITES, /* must wait for writeback before modifying
+ AS_RELEASE_ALWAYS = 6, /* Call ->release_folio(), even if no private data */
+ AS_STABLE_WRITES = 7, /* must wait for writeback before modifying
folio contents */
- AS_UNMOVABLE, /* The mapping cannot be moved, ever */
+ AS_UNMOVABLE = 8, /* The mapping cannot be moved, ever */
+ AS_FOLIO_ORDER_MIN = 16,
+ AS_FOLIO_ORDER_MAX = 21, /* Bits 16-25 are used for FOLIO_ORDER */
};
+#define AS_FOLIO_ORDER_MIN_MASK 0x001f0000
+#define AS_FOLIO_ORDER_MAX_MASK 0x03e00000
+#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
@@ -359,9 +364,48 @@ static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
#define MAX_PAGECACHE_ORDER 8
#endif
+/*
+ * mapping_set_folio_order_range() - Set the orders supported by a file.
+ * @mapping: The address space of the file.
+ * @min: Minimum folio order (between 0-MAX_PAGECACHE_ORDER inclusive).
+ * @max: Maximum folio order (between @min-MAX_PAGECACHE_ORDER inclusive).
+ *
+ * The filesystem should call this function in its inode constructor to
+ * indicate which base size (min) and maximum size (max) 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_order_range(struct address_space *mapping,
+ unsigned int min, unsigned int max)
+{
+ if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
+ return;
+
Errm. Sure? When transparent hugepages are _enabled_ we don't support
this feature?
Confused.
Cheers,
Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@xxxxxxx +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich
