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Date: Tue, 14 Jun 2011 03:49:44 -0700 (PDT)
From: Hugh Dickins <hughd@...gle.com>
To: Andrew Morton <akpm@...ux-foundation.org>
cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH 5/12] tmpfs: copy truncate_inode_pages_range
Bring truncate.c's code for truncate_inode_pages_range() inline into
shmem_truncate_range(), replacing its first call (there's a followup
call below, but leave that one, it will disappear next).
Don't play with it yet, apart from leaving out the cleancache flush,
and (importantly) the nrpages == 0 skip, and moving shmem_setattr()'s
partial page preparation into its partial page handling.
Signed-off-by: Hugh Dickins <hughd@...gle.com>
---
mm/shmem.c | 99 ++++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 79 insertions(+), 20 deletions(-)
--- linux.orig/mm/shmem.c 2011-06-13 13:28:25.822786909 -0700
+++ linux/mm/shmem.c 2011-06-13 13:28:44.330878656 -0700
@@ -50,6 +50,7 @@ static struct vfsmount *shm_mnt;
#include <linux/shmem_fs.h>
#include <linux/writeback.h>
#include <linux/blkdev.h>
+#include <linux/pagevec.h>
#include <linux/percpu_counter.h>
#include <linux/splice.h>
#include <linux/security.h>
@@ -242,11 +243,88 @@ void shmem_truncate_range(struct inode *
struct address_space *mapping = inode->i_mapping;
struct shmem_inode_info *info = SHMEM_I(inode);
pgoff_t start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+ unsigned partial = lstart & (PAGE_CACHE_SIZE - 1);
pgoff_t end = (lend >> PAGE_CACHE_SHIFT);
+ struct pagevec pvec;
pgoff_t index;
swp_entry_t swap;
+ int i;
- truncate_inode_pages_range(mapping, lstart, lend);
+ BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1));
+
+ pagevec_init(&pvec, 0);
+ index = start;
+ while (index <= end && pagevec_lookup(&pvec, mapping, index,
+ min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
+ mem_cgroup_uncharge_start();
+ for (i = 0; i < pagevec_count(&pvec); i++) {
+ struct page *page = pvec.pages[i];
+
+ /* We rely upon deletion not changing page->index */
+ index = page->index;
+ if (index > end)
+ break;
+
+ if (!trylock_page(page))
+ continue;
+ WARN_ON(page->index != index);
+ if (PageWriteback(page)) {
+ unlock_page(page);
+ continue;
+ }
+ truncate_inode_page(mapping, page);
+ unlock_page(page);
+ }
+ pagevec_release(&pvec);
+ mem_cgroup_uncharge_end();
+ cond_resched();
+ index++;
+ }
+
+ if (partial) {
+ struct page *page = NULL;
+ shmem_getpage(inode, start - 1, &page, SGP_READ, NULL);
+ if (page) {
+ zero_user_segment(page, partial, PAGE_CACHE_SIZE);
+ set_page_dirty(page);
+ unlock_page(page);
+ page_cache_release(page);
+ }
+ }
+
+ index = start;
+ for ( ; ; ) {
+ cond_resched();
+ if (!pagevec_lookup(&pvec, mapping, index,
+ min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
+ if (index == start)
+ break;
+ index = start;
+ continue;
+ }
+ if (index == start && pvec.pages[0]->index > end) {
+ pagevec_release(&pvec);
+ break;
+ }
+ mem_cgroup_uncharge_start();
+ for (i = 0; i < pagevec_count(&pvec); i++) {
+ struct page *page = pvec.pages[i];
+
+ /* We rely upon deletion not changing page->index */
+ index = page->index;
+ if (index > end)
+ break;
+
+ lock_page(page);
+ WARN_ON(page->index != index);
+ wait_on_page_writeback(page);
+ truncate_inode_page(mapping, page);
+ unlock_page(page);
+ }
+ pagevec_release(&pvec);
+ mem_cgroup_uncharge_end();
+ index++;
+ }
if (end > SHMEM_NR_DIRECT)
end = SHMEM_NR_DIRECT;
@@ -289,24 +367,7 @@ static int shmem_setattr(struct dentry *
if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
loff_t oldsize = inode->i_size;
loff_t newsize = attr->ia_size;
- struct page *page = NULL;
- if (newsize < oldsize) {
- /*
- * If truncating down to a partial page, then
- * if that page is already allocated, hold it
- * in memory until the truncation is over, so
- * truncate_partial_page cannot miss it were
- * it assigned to swap.
- */
- if (newsize & (PAGE_CACHE_SIZE-1)) {
- (void) shmem_getpage(inode,
- newsize >> PAGE_CACHE_SHIFT,
- &page, SGP_READ, NULL);
- if (page)
- unlock_page(page);
- }
- }
if (newsize != oldsize) {
i_size_write(inode, newsize);
inode->i_ctime = inode->i_mtime = CURRENT_TIME;
@@ -318,8 +379,6 @@ static int shmem_setattr(struct dentry *
/* unmap again to remove racily COWed private pages */
unmap_mapping_range(inode->i_mapping, holebegin, 0, 1);
}
- if (page)
- page_cache_release(page);
}
setattr_copy(inode, attr);
--
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