From: Vivek Goyal <vgoyal@redhat.com>
To: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-nvdimm@lists.01.org
Cc: virtio-fs@redhat.com, vgoyal@redhat.com, miklos@szeredi.hu,
stefanha@redhat.com, dgilbert@redhat.com,
Dan Williams <dan.j.williams@intel.com>
Subject: [PATCH 16/19] dax: Create a range version of dax_layout_busy_page()
Date: Wed, 21 Aug 2019 13:57:17 -0400 [thread overview]
Message-ID: <20190821175720.25901-17-vgoyal@redhat.com> (raw)
In-Reply-To: <20190821175720.25901-1-vgoyal@redhat.com>
While reclaiming a dax range, we do not want to unamap whole file instead
want to make sure pages in a certain range do not have references taken
on them. Hence create a version of the function which allows to pass in
a range.
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
fs/dax.c | 66 ++++++++++++++++++++++++++++++++-------------
include/linux/dax.h | 6 +++++
2 files changed, 54 insertions(+), 18 deletions(-)
diff --git a/fs/dax.c b/fs/dax.c
index 60620a37030c..435f5b67e828 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -557,27 +557,20 @@ static void *grab_mapping_entry(struct xa_state *xas,
return xa_mk_internal(VM_FAULT_FALLBACK);
}
-/**
- * dax_layout_busy_page - find first pinned page in @mapping
- * @mapping: address space to scan for a page with ref count > 1
- *
- * DAX requires ZONE_DEVICE mapped pages. These pages are never
- * 'onlined' to the page allocator so they are considered idle when
- * page->count == 1. A filesystem uses this interface to determine if
- * any page in the mapping is busy, i.e. for DMA, or other
- * get_user_pages() usages.
- *
- * It is expected that the filesystem is holding locks to block the
- * establishment of new mappings in this address_space. I.e. it expects
- * to be able to run unmap_mapping_range() and subsequently not race
- * mapping_mapped() becoming true.
+/*
+ * Partial pages are included. If end is 0, pages in the range from start
+ * to end of the file are inluded.
*/
-struct page *dax_layout_busy_page(struct address_space *mapping)
+struct page *dax_layout_busy_page_range(struct address_space *mapping,
+ loff_t start, loff_t end)
{
- XA_STATE(xas, &mapping->i_pages, 0);
void *entry;
unsigned int scanned = 0;
struct page *page = NULL;
+ pgoff_t start_idx = start >> PAGE_SHIFT;
+ pgoff_t end_idx = end >> PAGE_SHIFT;
+ XA_STATE(xas, &mapping->i_pages, start_idx);
+ loff_t len, lstart = round_down(start, PAGE_SIZE);
/*
* In the 'limited' case get_user_pages() for dax is disabled.
@@ -588,6 +581,22 @@ struct page *dax_layout_busy_page(struct address_space *mapping)
if (!dax_mapping(mapping) || !mapping_mapped(mapping))
return NULL;
+ /* If end == 0, all pages from start to till end of file */
+ if (!end) {
+ end_idx = ULONG_MAX;
+ len = 0;
+ } else {
+ /* length is being calculated from lstart and not start.
+ * This is due to behavior of unmap_mapping_range(). If
+ * start is say 4094 and end is on 4093 then want to
+ * unamp two pages, idx 0 and 1. But unmap_mapping_range()
+ * will unmap only page at idx 0. If we calculate len
+ * from the rounded down start, this problem should not
+ * happen.
+ */
+ len = end - lstart + 1;
+ }
+
/*
* If we race get_user_pages_fast() here either we'll see the
* elevated page count in the iteration and wait, or
@@ -600,10 +609,10 @@ struct page *dax_layout_busy_page(struct address_space *mapping)
* guaranteed to either see new references or prevent new
* references from being established.
*/
- unmap_mapping_range(mapping, 0, 0, 0);
+ unmap_mapping_range(mapping, start, len, 0);
xas_lock_irq(&xas);
- xas_for_each(&xas, entry, ULONG_MAX) {
+ xas_for_each(&xas, entry, end_idx) {
if (WARN_ON_ONCE(!xa_is_value(entry)))
continue;
if (unlikely(dax_is_locked(entry)))
@@ -624,6 +633,27 @@ struct page *dax_layout_busy_page(struct address_space *mapping)
xas_unlock_irq(&xas);
return page;
}
+EXPORT_SYMBOL_GPL(dax_layout_busy_page_range);
+
+/**
+ * dax_layout_busy_page - find first pinned page in @mapping
+ * @mapping: address space to scan for a page with ref count > 1
+ *
+ * DAX requires ZONE_DEVICE mapped pages. These pages are never
+ * 'onlined' to the page allocator so they are considered idle when
+ * page->count == 1. A filesystem uses this interface to determine if
+ * any page in the mapping is busy, i.e. for DMA, or other
+ * get_user_pages() usages.
+ *
+ * It is expected that the filesystem is holding locks to block the
+ * establishment of new mappings in this address_space. I.e. it expects
+ * to be able to run unmap_mapping_range() and subsequently not race
+ * mapping_mapped() becoming true.
+ */
+struct page *dax_layout_busy_page(struct address_space *mapping)
+{
+ return dax_layout_busy_page_range(mapping, 0, 0);
+}
EXPORT_SYMBOL_GPL(dax_layout_busy_page);
static int __dax_invalidate_entry(struct address_space *mapping,
diff --git a/include/linux/dax.h b/include/linux/dax.h
index e7f40108f2c9..3ef6686c080b 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -145,6 +145,7 @@ int dax_writeback_mapping_range(struct address_space *mapping,
struct writeback_control *wbc);
struct page *dax_layout_busy_page(struct address_space *mapping);
+struct page *dax_layout_busy_page_range(struct address_space *mapping, loff_t start, loff_t end);
dax_entry_t dax_lock_page(struct page *page);
void dax_unlock_page(struct page *page, dax_entry_t cookie);
#else
@@ -180,6 +181,11 @@ static inline struct page *dax_layout_busy_page(struct address_space *mapping)
return NULL;
}
+static inline struct page *dax_layout_busy_page_range(struct address_space *mapping, pgoff_t start, pgoff_t nr_pages)
+{
+ return NULL;
+}
+
static inline int dax_writeback_mapping_range(struct address_space *mapping,
struct block_device *bdev, struct dax_device *dax_dev,
struct writeback_control *wbc)
--
2.20.1
next prev parent reply other threads:[~2019-08-21 17:58 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-21 17:57 [PATCH v3 00/19][RFC] virtio-fs: Enable DAX support Vivek Goyal
2019-08-21 17:57 ` [PATCH 01/19] dax: remove block device dependencies Vivek Goyal
2019-08-26 11:51 ` Christoph Hellwig
2019-08-27 16:38 ` Vivek Goyal
2019-08-28 6:58 ` Christoph Hellwig
2019-08-28 17:58 ` Vivek Goyal
2019-08-28 22:53 ` Dave Chinner
2019-08-29 0:04 ` Dan Williams
2019-08-29 9:32 ` Christoph Hellwig
2019-12-16 18:10 ` Vivek Goyal
2020-01-07 12:51 ` Christoph Hellwig
2020-01-07 14:22 ` Dan Williams
2020-01-07 17:07 ` Darrick J. Wong
2020-01-07 17:29 ` Dan Williams
2020-01-07 18:01 ` Vivek Goyal
2020-01-07 18:07 ` Dan Williams
2020-01-07 18:33 ` Vivek Goyal
2020-01-07 18:49 ` Dan Williams
2020-01-07 19:02 ` Darrick J. Wong
2020-01-07 19:46 ` Dan Williams
2020-01-07 23:38 ` Dan Williams
2020-01-09 11:24 ` Jan Kara
2020-01-09 20:03 ` Dan Williams
2020-01-10 12:36 ` Christoph Hellwig
2020-01-14 20:31 ` Vivek Goyal
2020-01-14 20:39 ` Dan Williams
2020-01-14 21:28 ` Vivek Goyal
2020-01-14 22:23 ` Dan Williams
2020-01-15 19:56 ` Vivek Goyal
2020-01-15 20:17 ` Dan Williams
2020-01-15 21:08 ` Jeff Moyer
2020-01-16 18:09 ` Dan Williams
2020-01-16 18:39 ` Vivek Goyal
2020-01-16 19:09 ` Dan Williams
2020-01-16 19:23 ` Vivek Goyal
2020-02-11 17:33 ` Vivek Goyal
2020-01-15 9:03 ` Jan Kara
2019-08-21 17:57 ` [PATCH 02/19] dax: Pass dax_dev to dax_writeback_mapping_range() Vivek Goyal
2019-08-26 11:53 ` Christoph Hellwig
2019-08-26 20:33 ` Vivek Goyal
2019-08-26 20:58 ` Vivek Goyal
2019-08-26 21:33 ` Dan Williams
2019-08-28 6:58 ` Christoph Hellwig
2020-01-03 14:12 ` Vivek Goyal
2020-01-03 18:12 ` Dan Williams
2020-01-03 18:18 ` Dan Williams
2020-01-03 18:33 ` Vivek Goyal
2020-01-03 19:30 ` Dan Williams
2020-01-03 18:43 ` Vivek Goyal
2019-08-27 13:45 ` Jan Kara
2019-08-21 17:57 ` [PATCH 03/19] virtio: Add get_shm_region method Vivek Goyal
2019-08-21 17:57 ` [PATCH 04/19] virtio: Implement get_shm_region for PCI transport Vivek Goyal
2019-08-26 1:43 ` [Virtio-fs] " piaojun
2019-08-26 13:06 ` Vivek Goyal
2019-08-27 9:41 ` piaojun
2019-08-27 8:34 ` Cornelia Huck
2019-08-27 8:46 ` Cornelia Huck
2019-08-27 11:53 ` Vivek Goyal
2019-08-21 17:57 ` [PATCH 05/19] virtio: Implement get_shm_region for MMIO transport Vivek Goyal
2019-08-27 8:39 ` Cornelia Huck
2019-08-27 11:54 ` Vivek Goyal
2019-08-21 17:57 ` [PATCH 06/19] fuse, dax: add fuse_conn->dax_dev field Vivek Goyal
2019-08-21 17:57 ` [PATCH 07/19] virtio_fs, dax: Set up virtio_fs dax_device Vivek Goyal
2019-08-21 17:57 ` [PATCH 08/19] fuse: Keep a list of free dax memory ranges Vivek Goyal
2019-08-21 17:57 ` [PATCH 09/19] fuse: implement FUSE_INIT map_alignment field Vivek Goyal
2019-08-21 17:57 ` [PATCH 10/19] fuse: Introduce setupmapping/removemapping commands Vivek Goyal
2019-08-21 17:57 ` [PATCH 11/19] fuse, dax: Implement dax read/write operations Vivek Goyal
2019-08-21 19:49 ` Liu Bo
2019-08-22 12:59 ` Vivek Goyal
2019-08-21 17:57 ` [PATCH 12/19] fuse, dax: add DAX mmap support Vivek Goyal
2019-08-21 17:57 ` [PATCH 13/19] fuse: Define dax address space operations Vivek Goyal
2019-08-21 17:57 ` [PATCH 14/19] fuse, dax: Take ->i_mmap_sem lock during dax page fault Vivek Goyal
2019-08-21 17:57 ` [PATCH 15/19] fuse: Maintain a list of busy elements Vivek Goyal
2019-08-21 17:57 ` Vivek Goyal [this message]
2019-08-21 17:57 ` [PATCH 17/19] fuse: Add logic to free up a memory range Vivek Goyal
2019-08-21 17:57 ` [PATCH 18/19] fuse: Release file in process context Vivek Goyal
2019-08-21 17:57 ` [PATCH 19/19] fuse: Take inode lock for dax inode truncation Vivek Goyal
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