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Message-Id: <1617140178-8773-7-git-send-email-anthony.yznaga@oracle.com>
Date: Tue, 30 Mar 2021 14:35:41 -0700
From: Anthony Yznaga <anthony.yznaga@...cle.com>
To: linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc: willy@...radead.org, corbet@....net, tglx@...utronix.de,
mingo@...hat.com, bp@...en8.de, x86@...nel.org, hpa@...or.com,
dave.hansen@...ux.intel.com, luto@...nel.org, peterz@...radead.org,
rppt@...nel.org, akpm@...ux-foundation.org, hughd@...gle.com,
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linux-doc@...r.kernel.org, kexec@...ts.infradead.org
Subject: [RFC v2 06/43] mm: PKRAM: implement byte stream operations
This patch adds the ability to save an arbitrary byte streams to a
a PKRAM object using pkram_write() to be restored later using pkram_read().
Originally-by: Vladimir Davydov <vdavydov.dev@...il.com>
Signed-off-by: Anthony Yznaga <anthony.yznaga@...cle.com>
---
include/linux/pkram.h | 11 +++++
mm/pkram.c | 123 ++++++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 130 insertions(+), 4 deletions(-)
diff --git a/include/linux/pkram.h b/include/linux/pkram.h
index 9d8a6fd96dd9..4f95d4fb5339 100644
--- a/include/linux/pkram.h
+++ b/include/linux/pkram.h
@@ -14,10 +14,12 @@
* enum pkram_data_flags - definition of data types contained in a pkram obj
* @PKRAM_DATA_none: No data types configured
* @PKRAM_DATA_pages: obj contains file page data
+ * @PKRAM_DATA_bytes: obj contains byte data
*/
enum pkram_data_flags {
PKRAM_DATA_none = 0x0, /* No data types configured */
PKRAM_DATA_pages = 0x1, /* Contains file page data */
+ PKRAM_DATA_bytes = 0x2, /* Contains byte data */
};
struct pkram_data_stream {
@@ -36,18 +38,27 @@ struct pkram_stream {
__u64 *pages_head_link_pfnp;
__u64 *pages_tail_link_pfnp;
+
+ __u64 *bytes_head_link_pfnp;
+ __u64 *bytes_tail_link_pfnp;
};
struct pkram_pages_access {
unsigned long next_index;
};
+struct pkram_bytes_access {
+ struct page *data_page; /* current page */
+ unsigned int data_offset; /* offset into current page */
+};
+
struct pkram_access {
enum pkram_data_flags dtype;
struct pkram_stream *ps;
struct pkram_data_stream pds;
struct pkram_pages_access pages;
+ struct pkram_bytes_access bytes;
};
#define PKRAM_NAME_MAX 256 /* including nul */
diff --git a/mm/pkram.c b/mm/pkram.c
index da44a6060c5f..d81af26c9a66 100644
--- a/mm/pkram.c
+++ b/mm/pkram.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/err.h>
#include <linux/gfp.h>
+#include <linux/highmem.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/list.h>
@@ -46,6 +47,9 @@ struct pkram_link {
struct pkram_obj {
__u64 pages_head_link_pfn; /* the first pages link of the object */
__u64 pages_tail_link_pfn; /* the last pages link of the object */
+ __u64 bytes_head_link_pfn; /* the first bytes link of the object */
+ __u64 bytes_tail_link_pfn; /* the last bytes link of the object */
+ __u64 data_len; /* byte data size */
__u64 obj_pfn; /* points to the next object in the list */
};
@@ -140,6 +144,11 @@ static void pkram_truncate_obj(struct pkram_obj *obj)
pkram_truncate_links(obj->pages_head_link_pfn);
obj->pages_head_link_pfn = 0;
obj->pages_tail_link_pfn = 0;
+
+ pkram_truncate_links(obj->bytes_head_link_pfn);
+ obj->bytes_head_link_pfn = 0;
+ obj->bytes_tail_link_pfn = 0;
+ obj->data_len = 0;
}
static void pkram_truncate_node(struct pkram_node *node)
@@ -315,7 +324,7 @@ int pkram_prepare_save_obj(struct pkram_stream *ps, enum pkram_data_flags flags)
BUG_ON((node->flags & PKRAM_ACCMODE_MASK) != PKRAM_SAVE);
- if (flags & ~PKRAM_DATA_pages)
+ if (flags & ~(PKRAM_DATA_pages | PKRAM_DATA_bytes))
return -EINVAL;
page = pkram_alloc_page(ps->gfp_mask | __GFP_ZERO);
@@ -331,6 +340,10 @@ int pkram_prepare_save_obj(struct pkram_stream *ps, enum pkram_data_flags flags)
ps->pages_head_link_pfnp = &obj->pages_head_link_pfn;
ps->pages_tail_link_pfnp = &obj->pages_tail_link_pfn;
}
+ if (flags & PKRAM_DATA_bytes) {
+ ps->bytes_head_link_pfnp = &obj->bytes_head_link_pfn;
+ ps->bytes_tail_link_pfnp = &obj->bytes_tail_link_pfn;
+ }
ps->obj = obj;
return 0;
}
@@ -438,7 +451,7 @@ int pkram_prepare_load_obj(struct pkram_stream *ps)
return -ENODATA;
obj = pfn_to_kaddr(node->obj_pfn);
- if (!obj->pages_head_link_pfn) {
+ if (!obj->pages_head_link_pfn && !obj->bytes_head_link_pfn) {
WARN_ON(1);
return -EINVAL;
}
@@ -449,6 +462,10 @@ int pkram_prepare_load_obj(struct pkram_stream *ps)
ps->pages_head_link_pfnp = &obj->pages_head_link_pfn;
ps->pages_tail_link_pfnp = &obj->pages_tail_link_pfn;
}
+ if (obj->bytes_head_link_pfn) {
+ ps->bytes_head_link_pfnp = &obj->bytes_head_link_pfn;
+ ps->bytes_tail_link_pfnp = &obj->bytes_tail_link_pfn;
+ }
ps->obj = obj;
return 0;
}
@@ -499,6 +516,9 @@ void pkram_finish_access(struct pkram_access *pa, bool status_ok)
if (pa->pds.link)
pkram_truncate_link(pa->pds.link);
+
+ if ((pa->dtype == PKRAM_DATA_bytes) && (pa->bytes.data_page))
+ pkram_free_page(page_address(pa->bytes.data_page));
}
/*
@@ -552,6 +572,22 @@ int pkram_save_file_page(struct pkram_access *pa, struct page *page)
return __pkram_save_page(pa, page, page->index);
}
+static int __pkram_bytes_save_page(struct pkram_access *pa, struct page *page)
+{
+ struct pkram_data_stream *pds = &pa->pds;
+ struct pkram_link *link = pds->link;
+
+ if (!link || pds->entry_idx >= PKRAM_LINK_ENTRIES_MAX) {
+ link = pkram_new_link(pds, pa->ps->gfp_mask);
+ if (!link)
+ return -ENOMEM;
+ }
+
+ pkram_add_link_entry(pds, page);
+
+ return 0;
+}
+
static struct page *__pkram_prep_load_page(pkram_entry_t p)
{
struct page *page;
@@ -646,10 +682,53 @@ struct page *pkram_load_file_page(struct pkram_access *pa, unsigned long *index)
*
* On success, returns the number of bytes written, which is always equal to
* @count. On failure, -errno is returned.
+ *
+ * Error values:
+ * %ENOMEM: insufficient amount of memory available
*/
ssize_t pkram_write(struct pkram_access *pa, const void *buf, size_t count)
{
- return -ENOSYS;
+ struct pkram_node *node = pa->ps->node;
+ struct pkram_obj *obj = pa->ps->obj;
+ size_t copy_count, write_count = 0;
+ void *addr;
+
+ BUG_ON((node->flags & PKRAM_ACCMODE_MASK) != PKRAM_SAVE);
+
+ while (count > 0) {
+ if (!pa->bytes.data_page) {
+ gfp_t gfp_mask = pa->ps->gfp_mask;
+ struct page *page;
+ int err;
+
+ page = pkram_alloc_page((gfp_mask & GFP_RECLAIM_MASK) |
+ __GFP_HIGHMEM | __GFP_ZERO);
+ if (!page)
+ return -ENOMEM;
+ err = __pkram_bytes_save_page(pa, page);
+ if (err) {
+ pkram_free_page(page_address(page));
+ return err;
+ }
+ pa->bytes.data_page = page;
+ pa->bytes.data_offset = 0;
+ }
+
+ copy_count = min_t(size_t, count, PAGE_SIZE - pa->bytes.data_offset);
+ addr = kmap_atomic(pa->bytes.data_page);
+ memcpy(addr + pa->bytes.data_offset, buf, copy_count);
+ kunmap_atomic(addr);
+
+ buf += copy_count;
+ obj->data_len += copy_count;
+ pa->bytes.data_offset += copy_count;
+ if (pa->bytes.data_offset >= PAGE_SIZE)
+ pa->bytes.data_page = NULL;
+
+ write_count += copy_count;
+ count -= copy_count;
+ }
+ return write_count;
}
/**
@@ -663,5 +742,41 @@ ssize_t pkram_write(struct pkram_access *pa, const void *buf, size_t count)
*/
size_t pkram_read(struct pkram_access *pa, void *buf, size_t count)
{
- return 0;
+ struct pkram_node *node = pa->ps->node;
+ struct pkram_obj *obj = pa->ps->obj;
+ size_t copy_count, read_count = 0;
+ char *addr;
+
+ BUG_ON((node->flags & PKRAM_ACCMODE_MASK) != PKRAM_LOAD);
+
+ while (count > 0 && obj->data_len > 0) {
+ if (!pa->bytes.data_page) {
+ struct page *page;
+
+ page = __pkram_load_page(pa, NULL);
+ if (!page)
+ break;
+ pa->bytes.data_page = page;
+ pa->bytes.data_offset = 0;
+ }
+
+ copy_count = min_t(size_t, count, PAGE_SIZE - pa->bytes.data_offset);
+ if (copy_count > obj->data_len)
+ copy_count = obj->data_len;
+ addr = kmap_atomic(pa->bytes.data_page);
+ memcpy(buf, addr + pa->bytes.data_offset, copy_count);
+ kunmap_atomic(addr);
+
+ buf += copy_count;
+ obj->data_len -= copy_count;
+ pa->bytes.data_offset += copy_count;
+ if (pa->bytes.data_offset >= PAGE_SIZE || !obj->data_len) {
+ put_page(pa->bytes.data_page);
+ pa->bytes.data_page = NULL;
+ }
+
+ read_count += copy_count;
+ count -= copy_count;
+ }
+ return read_count;
}
--
1.8.3.1
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