From 102a0743326a03cd1a1202ceda21e175b7d3575c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:20:52 +0000
Subject: [PATCH] add new system file
---
kernel/mm/readahead.c | 383 ++++++++++++++++++++++++++++++++----------------------
1 files changed, 224 insertions(+), 159 deletions(-)
diff --git a/kernel/mm/readahead.c b/kernel/mm/readahead.c
index 4e63014..7bb2c3e 100644
--- a/kernel/mm/readahead.c
+++ b/kernel/mm/readahead.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
/*
* mm/readahead.c - address_space-level file readahead.
*
@@ -21,8 +22,14 @@
#include <linux/mm_inline.h>
#include <linux/blk-cgroup.h>
#include <linux/fadvise.h>
+#include <linux/sched/mm.h>
+#include <trace/hooks/mm.h>
#include "internal.h"
+
+#if defined(CONFIG_ARCH_ROCKCHIP) && defined(CONFIG_NO_GKI)
+#include <linux/fscrypt.h>
+#endif
/*
* Initialise a struct file's readahead state. Assumes that the caller has
@@ -81,6 +88,8 @@
* @data: private data for the callback routine.
*
* Hides the details of the LRU cache etc from the filesystems.
+ *
+ * Returns: %0 on success, error return by @filler otherwise
*/
int read_cache_pages(struct address_space *mapping, struct list_head *pages,
int (*filler)(void *, struct page *), void *data)
@@ -110,96 +119,129 @@
EXPORT_SYMBOL(read_cache_pages);
-static int read_pages(struct address_space *mapping, struct file *filp,
- struct list_head *pages, unsigned int nr_pages, gfp_t gfp)
+gfp_t readahead_gfp_mask(struct address_space *x)
{
+ gfp_t mask = mapping_gfp_mask(x) | __GFP_NORETRY | __GFP_NOWARN;
+
+ trace_android_rvh_set_readahead_gfp_mask(&mask);
+ return mask;
+}
+EXPORT_SYMBOL_GPL(readahead_gfp_mask);
+
+static void read_pages(struct readahead_control *rac, struct list_head *pages,
+ bool skip_page)
+{
+ const struct address_space_operations *aops = rac->mapping->a_ops;
+ struct page *page;
struct blk_plug plug;
- unsigned page_idx;
- int ret;
+
+ if (!readahead_count(rac))
+ goto out;
blk_start_plug(&plug);
- if (mapping->a_ops->readpages) {
- ret = mapping->a_ops->readpages(filp, mapping, pages, nr_pages);
+ if (aops->readahead) {
+ aops->readahead(rac);
+ /* Clean up the remaining pages */
+ while ((page = readahead_page(rac))) {
+ unlock_page(page);
+ put_page(page);
+ }
+ } else if (aops->readpages) {
+ aops->readpages(rac->file, rac->mapping, pages,
+ readahead_count(rac));
/* Clean up the remaining pages */
put_pages_list(pages);
- goto out;
+ rac->_index += rac->_nr_pages;
+ rac->_nr_pages = 0;
+ } else {
+ while ((page = readahead_page(rac))) {
+ aops->readpage(rac->file, page);
+ put_page(page);
+ }
}
- for (page_idx = 0; page_idx < nr_pages; page_idx++) {
- struct page *page = lru_to_page(pages);
- list_del(&page->lru);
- if (!add_to_page_cache_lru(page, mapping, page->index, gfp))
- mapping->a_ops->readpage(filp, page);
- put_page(page);
- }
- ret = 0;
-
-out:
blk_finish_plug(&plug);
- return ret;
+ BUG_ON(!list_empty(pages));
+ BUG_ON(readahead_count(rac));
+
+out:
+ if (skip_page)
+ rac->_index++;
}
-/*
- * __do_page_cache_readahead() actually reads a chunk of disk. It allocates
- * the pages first, then submits them for I/O. This avoids the very bad
- * behaviour which would occur if page allocations are causing VM writeback.
- * We really don't want to intermingle reads and writes like that.
+/**
+ * page_cache_ra_unbounded - Start unchecked readahead.
+ * @ractl: Readahead control.
+ * @nr_to_read: The number of pages to read.
+ * @lookahead_size: Where to start the next readahead.
*
- * Returns the number of pages requested, or the maximum amount of I/O allowed.
+ * This function is for filesystems to call when they want to start
+ * readahead beyond a file's stated i_size. This is almost certainly
+ * not the function you want to call. Use page_cache_async_readahead()
+ * or page_cache_sync_readahead() instead.
+ *
+ * Context: File is referenced by caller. Mutexes may be held by caller.
+ * May sleep, but will not reenter filesystem to reclaim memory.
*/
-unsigned int __do_page_cache_readahead(struct address_space *mapping,
- struct file *filp, pgoff_t offset, unsigned long nr_to_read,
- unsigned long lookahead_size)
+void page_cache_ra_unbounded(struct readahead_control *ractl,
+ unsigned long nr_to_read, unsigned long lookahead_size)
{
- struct inode *inode = mapping->host;
- struct page *page;
- unsigned long end_index; /* The last page we want to read */
+ struct address_space *mapping = ractl->mapping;
+ unsigned long index = readahead_index(ractl);
LIST_HEAD(page_pool);
- int page_idx;
- unsigned int nr_pages = 0;
- loff_t isize = i_size_read(inode);
gfp_t gfp_mask = readahead_gfp_mask(mapping);
+ unsigned long i;
- if (isize == 0)
- goto out;
-
- end_index = ((isize - 1) >> PAGE_SHIFT);
+ /*
+ * Partway through the readahead operation, we will have added
+ * locked pages to the page cache, but will not yet have submitted
+ * them for I/O. Adding another page may need to allocate memory,
+ * which can trigger memory reclaim. Telling the VM we're in
+ * the middle of a filesystem operation will cause it to not
+ * touch file-backed pages, preventing a deadlock. Most (all?)
+ * filesystems already specify __GFP_NOFS in their mapping's
+ * gfp_mask, but let's be explicit here.
+ */
+ unsigned int nofs = memalloc_nofs_save();
/*
* Preallocate as many pages as we will need.
*/
- for (page_idx = 0; page_idx < nr_to_read; page_idx++) {
- pgoff_t page_offset = offset + page_idx;
+ for (i = 0; i < nr_to_read; i++) {
+ struct page *page = xa_load(&mapping->i_pages, index + i);
- if (page_offset > end_index)
- break;
+ BUG_ON(index + i != ractl->_index + ractl->_nr_pages);
- rcu_read_lock();
- page = radix_tree_lookup(&mapping->i_pages, page_offset);
- rcu_read_unlock();
- if (page && !radix_tree_exceptional_entry(page)) {
+ if (page && !xa_is_value(page)) {
/*
- * Page already present? Kick off the current batch of
- * contiguous pages before continuing with the next
- * batch.
+ * Page already present? Kick off the current batch
+ * of contiguous pages before continuing with the
+ * next batch. This page may be the one we would
+ * have intended to mark as Readahead, but we don't
+ * have a stable reference to this page, and it's
+ * not worth getting one just for that.
*/
- if (nr_pages)
- read_pages(mapping, filp, &page_pool, nr_pages,
- gfp_mask);
- nr_pages = 0;
+ read_pages(ractl, &page_pool, true);
continue;
}
page = __page_cache_alloc(gfp_mask);
if (!page)
break;
- page->index = page_offset;
- list_add(&page->lru, &page_pool);
- if (page_idx == nr_to_read - lookahead_size)
+ if (mapping->a_ops->readpages) {
+ page->index = index + i;
+ list_add(&page->lru, &page_pool);
+ } else if (add_to_page_cache_lru(page, mapping, index + i,
+ gfp_mask) < 0) {
+ put_page(page);
+ read_pages(ractl, &page_pool, true);
+ continue;
+ }
+ if (i == nr_to_read - lookahead_size)
SetPageReadahead(page);
- nr_pages++;
+ ractl->_nr_pages++;
}
/*
@@ -207,44 +249,88 @@
* uptodate then the caller will launch readpage again, and
* will then handle the error.
*/
- if (nr_pages)
- read_pages(mapping, filp, &page_pool, nr_pages, gfp_mask);
- BUG_ON(!list_empty(&page_pool));
-out:
- return nr_pages;
+ read_pages(ractl, &page_pool, false);
+ memalloc_nofs_restore(nofs);
+}
+EXPORT_SYMBOL_GPL(page_cache_ra_unbounded);
+
+/*
+ * do_page_cache_ra() actually reads a chunk of disk. It allocates
+ * the pages first, then submits them for I/O. This avoids the very bad
+ * behaviour which would occur if page allocations are causing VM writeback.
+ * We really don't want to intermingle reads and writes like that.
+ */
+void do_page_cache_ra(struct readahead_control *ractl,
+ unsigned long nr_to_read, unsigned long lookahead_size)
+{
+ struct inode *inode = ractl->mapping->host;
+ unsigned long index = readahead_index(ractl);
+ loff_t isize = i_size_read(inode);
+ pgoff_t end_index; /* The last page we want to read */
+
+ if (isize == 0)
+ return;
+
+ end_index = (isize - 1) >> PAGE_SHIFT;
+ if (index > end_index)
+ return;
+ /* Don't read past the page containing the last byte of the file */
+ if (nr_to_read > end_index - index)
+ nr_to_read = end_index - index + 1;
+
+ page_cache_ra_unbounded(ractl, nr_to_read, lookahead_size);
}
/*
* Chunk the readahead into 2 megabyte units, so that we don't pin too much
* memory at once.
*/
-int force_page_cache_readahead(struct address_space *mapping, struct file *filp,
- pgoff_t offset, unsigned long nr_to_read)
+void force_page_cache_ra(struct readahead_control *ractl,
+ struct file_ra_state *ra, unsigned long nr_to_read)
{
+ struct address_space *mapping = ractl->mapping;
struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
- struct file_ra_state *ra = &filp->f_ra;
- unsigned long max_pages;
+ unsigned long max_pages, index;
+#if defined(CONFIG_ARCH_ROCKCHIP) && defined(CONFIG_NO_GKI)
+ bool force_lookahead = false;
+#endif
- if (unlikely(!mapping->a_ops->readpage && !mapping->a_ops->readpages))
- return -EINVAL;
+ if (unlikely(!mapping->a_ops->readpage && !mapping->a_ops->readpages &&
+ !mapping->a_ops->readahead))
+ return;
/*
* If the request exceeds the readahead window, allow the read to
* be up to the optimal hardware IO size
*/
+ index = readahead_index(ractl);
max_pages = max_t(unsigned long, bdi->io_pages, ra->ra_pages);
- nr_to_read = min(nr_to_read, max_pages);
+#if defined(CONFIG_ARCH_ROCKCHIP) && defined(CONFIG_NO_GKI)
+ /* For files with fscrypt enabled, to allow IO and the encryption
+ * or decryption process to ping-pong, lookahead is forcibly enabled.
+ */
+ if (nr_to_read > max_pages && fscrypt_inode_uses_fs_layer_crypto(mapping->host))
+ force_lookahead = true;
+#endif
+ nr_to_read = min_t(unsigned long, nr_to_read, max_pages);
while (nr_to_read) {
unsigned long this_chunk = (2 * 1024 * 1024) / PAGE_SIZE;
if (this_chunk > nr_to_read)
this_chunk = nr_to_read;
- __do_page_cache_readahead(mapping, filp, offset, this_chunk, 0);
+ ractl->_index = index;
+#if defined(CONFIG_ARCH_ROCKCHIP) && defined(CONFIG_NO_GKI)
+ if (force_lookahead)
+ do_page_cache_ra(ractl, this_chunk, this_chunk / 2);
+ else
+ do_page_cache_ra(ractl, this_chunk, 0);
+#else
+ do_page_cache_ra(ractl, this_chunk, 0);
+#endif
- offset += this_chunk;
+ index += this_chunk;
nr_to_read -= this_chunk;
}
- return 0;
}
/*
@@ -272,17 +358,15 @@
* return it as the new window size.
*/
static unsigned long get_next_ra_size(struct file_ra_state *ra,
- unsigned long max)
+ unsigned long max)
{
unsigned long cur = ra->size;
- unsigned long newsize;
if (cur < max / 16)
- newsize = 4 * cur;
- else
- newsize = 2 * cur;
-
- return min(newsize, max);
+ return 4 * cur;
+ if (cur <= max / 2)
+ return 2 * cur;
+ return max;
}
/*
@@ -325,21 +409,21 @@
*/
/*
- * Count contiguously cached pages from @offset-1 to @offset-@max,
+ * Count contiguously cached pages from @index-1 to @index-@max,
* this count is a conservative estimation of
* - length of the sequential read sequence, or
* - thrashing threshold in memory tight systems
*/
static pgoff_t count_history_pages(struct address_space *mapping,
- pgoff_t offset, unsigned long max)
+ pgoff_t index, unsigned long max)
{
pgoff_t head;
rcu_read_lock();
- head = page_cache_prev_hole(mapping, offset - 1, max);
+ head = page_cache_prev_miss(mapping, index - 1, max);
rcu_read_unlock();
- return offset - 1 - head;
+ return index - 1 - head;
}
/*
@@ -347,13 +431,13 @@
*/
static int try_context_readahead(struct address_space *mapping,
struct file_ra_state *ra,
- pgoff_t offset,
+ pgoff_t index,
unsigned long req_size,
unsigned long max)
{
pgoff_t size;
- size = count_history_pages(mapping, offset, max);
+ size = count_history_pages(mapping, index, max);
/*
* not enough history pages:
@@ -366,10 +450,10 @@
* starts from beginning of file:
* it is a strong indication of long-run stream (or whole-file-read)
*/
- if (size >= offset)
+ if (size >= index)
size *= 2;
- ra->start = offset;
+ ra->start = index;
ra->size = min(size + req_size, max);
ra->async_size = 1;
@@ -379,16 +463,15 @@
/*
* A minimal readahead algorithm for trivial sequential/random reads.
*/
-static unsigned long
-ondemand_readahead(struct address_space *mapping,
- struct file_ra_state *ra, struct file *filp,
- bool hit_readahead_marker, pgoff_t offset,
- unsigned long req_size)
+static void ondemand_readahead(struct readahead_control *ractl,
+ struct file_ra_state *ra, bool hit_readahead_marker,
+ unsigned long req_size)
{
- struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
+ struct backing_dev_info *bdi = inode_to_bdi(ractl->mapping->host);
unsigned long max_pages = ra->ra_pages;
unsigned long add_pages;
- pgoff_t prev_offset;
+ unsigned long index = readahead_index(ractl);
+ pgoff_t prev_index;
/*
* If the request exceeds the readahead window, allow the read to
@@ -397,18 +480,20 @@
if (req_size > max_pages && bdi->io_pages > max_pages)
max_pages = min(req_size, bdi->io_pages);
+ trace_android_vh_ra_tuning_max_page(ractl, &max_pages);
+
/*
* start of file
*/
- if (!offset)
+ if (!index)
goto initial_readahead;
/*
- * It's the expected callback offset, assume sequential access.
+ * It's the expected callback index, assume sequential access.
* Ramp up sizes, and push forward the readahead window.
*/
- if ((offset == (ra->start + ra->size - ra->async_size) ||
- offset == (ra->start + ra->size))) {
+ if ((index == (ra->start + ra->size - ra->async_size) ||
+ index == (ra->start + ra->size))) {
ra->start += ra->size;
ra->size = get_next_ra_size(ra, max_pages);
ra->async_size = ra->size;
@@ -425,14 +510,15 @@
pgoff_t start;
rcu_read_lock();
- start = page_cache_next_hole(mapping, offset + 1, max_pages);
+ start = page_cache_next_miss(ractl->mapping, index + 1,
+ max_pages);
rcu_read_unlock();
- if (!start || start - offset > max_pages)
- return 0;
+ if (!start || start - index > max_pages)
+ return;
ra->start = start;
- ra->size = start - offset; /* old async_size */
+ ra->size = start - index; /* old async_size */
ra->size += req_size;
ra->size = get_next_ra_size(ra, max_pages);
ra->async_size = ra->size;
@@ -447,28 +533,30 @@
/*
* sequential cache miss
- * trivial case: (offset - prev_offset) == 1
- * unaligned reads: (offset - prev_offset) == 0
+ * trivial case: (index - prev_index) == 1
+ * unaligned reads: (index - prev_index) == 0
*/
- prev_offset = (unsigned long long)ra->prev_pos >> PAGE_SHIFT;
- if (offset - prev_offset <= 1UL)
+ prev_index = (unsigned long long)ra->prev_pos >> PAGE_SHIFT;
+ if (index - prev_index <= 1UL)
goto initial_readahead;
/*
* Query the page cache and look for the traces(cached history pages)
* that a sequential stream would leave behind.
*/
- if (try_context_readahead(mapping, ra, offset, req_size, max_pages))
+ if (try_context_readahead(ractl->mapping, ra, index, req_size,
+ max_pages))
goto readit;
/*
* standalone, small random read
* Read as is, and do not pollute the readahead state.
*/
- return __do_page_cache_readahead(mapping, filp, offset, req_size, 0);
+ do_page_cache_ra(ractl, req_size, 0);
+ return;
initial_readahead:
- ra->start = offset;
+ ra->start = index;
ra->size = get_init_ra_size(req_size, max_pages);
ra->async_size = ra->size > req_size ? ra->size - req_size : ra->size;
@@ -479,7 +567,7 @@
* the resulted next readahead window into the current one.
* Take care of maximum IO pages as above.
*/
- if (offset == ra->start && ra->size == ra->async_size) {
+ if (index == ra->start && ra->size == ra->async_size) {
add_pages = get_next_ra_size(ra, max_pages);
if (ra->size + add_pages <= max_pages) {
ra->async_size = add_pages;
@@ -490,65 +578,42 @@
}
}
- return ra_submit(ra, mapping, filp);
+ ractl->_index = ra->start;
+ do_page_cache_ra(ractl, ra->size, ra->async_size);
}
-/**
- * page_cache_sync_readahead - generic file readahead
- * @mapping: address_space which holds the pagecache and I/O vectors
- * @ra: file_ra_state which holds the readahead state
- * @filp: passed on to ->readpage() and ->readpages()
- * @offset: start offset into @mapping, in pagecache page-sized units
- * @req_size: hint: total size of the read which the caller is performing in
- * pagecache pages
- *
- * page_cache_sync_readahead() should be called when a cache miss happened:
- * it will submit the read. The readahead logic may decide to piggyback more
- * pages onto the read request if access patterns suggest it will improve
- * performance.
- */
-void page_cache_sync_readahead(struct address_space *mapping,
- struct file_ra_state *ra, struct file *filp,
- pgoff_t offset, unsigned long req_size)
+void page_cache_sync_ra(struct readahead_control *ractl,
+ struct file_ra_state *ra, unsigned long req_count)
{
- /* no read-ahead */
- if (!ra->ra_pages)
- return;
+ bool do_forced_ra = ractl->file && (ractl->file->f_mode & FMODE_RANDOM);
- if (blk_cgroup_congested())
- return;
+ /*
+ * Even if read-ahead is disabled, issue this request as read-ahead
+ * as we'll need it to satisfy the requested range. The forced
+ * read-ahead will do the right thing and limit the read to just the
+ * requested range, which we'll set to 1 page for this case.
+ */
+ if (!ra->ra_pages || blk_cgroup_congested()) {
+ if (!ractl->file)
+ return;
+ req_count = 1;
+ do_forced_ra = true;
+ }
/* be dumb */
- if (filp && (filp->f_mode & FMODE_RANDOM)) {
- force_page_cache_readahead(mapping, filp, offset, req_size);
+ if (do_forced_ra) {
+ force_page_cache_ra(ractl, ra, req_count);
return;
}
/* do read-ahead */
- ondemand_readahead(mapping, ra, filp, false, offset, req_size);
+ ondemand_readahead(ractl, ra, false, req_count);
}
-EXPORT_SYMBOL_GPL(page_cache_sync_readahead);
+EXPORT_SYMBOL_GPL(page_cache_sync_ra);
-/**
- * page_cache_async_readahead - file readahead for marked pages
- * @mapping: address_space which holds the pagecache and I/O vectors
- * @ra: file_ra_state which holds the readahead state
- * @filp: passed on to ->readpage() and ->readpages()
- * @page: the page at @offset which has the PG_readahead flag set
- * @offset: start offset into @mapping, in pagecache page-sized units
- * @req_size: hint: total size of the read which the caller is performing in
- * pagecache pages
- *
- * page_cache_async_readahead() should be called when a page is used which
- * has the PG_readahead flag; this is a marker to suggest that the application
- * has used up enough of the readahead window that we should start pulling in
- * more pages.
- */
-void
-page_cache_async_readahead(struct address_space *mapping,
- struct file_ra_state *ra, struct file *filp,
- struct page *page, pgoff_t offset,
- unsigned long req_size)
+void page_cache_async_ra(struct readahead_control *ractl,
+ struct file_ra_state *ra, struct page *page,
+ unsigned long req_count)
{
/* no read-ahead */
if (!ra->ra_pages)
@@ -565,16 +630,16 @@
/*
* Defer asynchronous read-ahead on IO congestion.
*/
- if (inode_read_congested(mapping->host))
+ if (inode_read_congested(ractl->mapping->host))
return;
if (blk_cgroup_congested())
return;
/* do read-ahead */
- ondemand_readahead(mapping, ra, filp, true, offset, req_size);
+ ondemand_readahead(ractl, ra, true, req_count);
}
-EXPORT_SYMBOL_GPL(page_cache_async_readahead);
+EXPORT_SYMBOL_GPL(page_cache_async_ra);
ssize_t ksys_readahead(int fd, loff_t offset, size_t count)
{
--
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