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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@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hugh Dickins 2011-08-03 16:21:21 -07:00 committed by Linus Torvalds
parent 41ffe5d5ce
commit bda97eab0c
1 changed files with 79 additions and 20 deletions
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99
mm/shmem.c
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@ -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 *inode, loff_t lstart, loff_t lend)
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 *dentry, struct iattr *attr)
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 *dentry, struct iattr *attr)
/* 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);