From: Hugh Dickins <hughd@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@infradead.org>,
Cong Wang <amwang@redhat.com>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH 4/10] tmpfs: support fallocate FALLOC_FL_PUNCH_HOLE
Date: Sat, 12 May 2012 05:05:51 -0700 (PDT) [thread overview]
Message-ID: <alpine.LSU.2.00.1205120504230.28861@eggly.anvils> (raw)
In-Reply-To: <alpine.LSU.2.00.1205120447380.28861@eggly.anvils>
tmpfs has supported hole-punching since 2.6.16, via madvise(,,MADV_REMOVE).
But nowadays fallocate(,FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE,,) is the
agreed way to punch holes.
So add shmem_fallocate() to support that, and tweak shmem_truncate_range()
to support partial pages at both the beginning and end of range (never
needed for madvise, which demands rounded addr and rounds up length).
Based-on-patch-by: Cong Wang <amwang@redhat.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
---
mm/shmem.c | 68 ++++++++++++++++++++++++++++++++++++++++++---------
1 file changed, 57 insertions(+), 11 deletions(-)
--- 3045N.orig/mm/shmem.c 2012-05-05 10:46:12.316062172 -0700
+++ 3045N/mm/shmem.c 2012-05-05 10:46:18.768062321 -0700
@@ -53,6 +53,7 @@ static struct vfsmount *shm_mnt;
#include <linux/blkdev.h>
#include <linux/pagevec.h>
#include <linux/percpu_counter.h>
+#include <linux/falloc.h>
#include <linux/splice.h>
#include <linux/security.h>
#include <linux/swapops.h>
@@ -432,21 +433,23 @@ 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);
+ pgoff_t end = (lend + 1) >> PAGE_CACHE_SHIFT;
+ unsigned int partial_start = lstart & (PAGE_CACHE_SIZE - 1);
+ unsigned int partial_end = (lend + 1) & (PAGE_CACHE_SIZE - 1);
struct pagevec pvec;
pgoff_t indices[PAGEVEC_SIZE];
long nr_swaps_freed = 0;
pgoff_t index;
int i;
- BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1));
+ if (lend == -1)
+ end = -1; /* unsigned, so actually very big */
pagevec_init(&pvec, 0);
index = start;
- while (index <= end) {
+ while (index < end) {
pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
- min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1,
+ min(end - index, (pgoff_t)PAGEVEC_SIZE),
pvec.pages, indices);
if (!pvec.nr)
break;
@@ -455,7 +458,7 @@ void shmem_truncate_range(struct inode *
struct page *page = pvec.pages[i];
index = indices[i];
- if (index > end)
+ if (index >= end)
break;
if (radix_tree_exceptional_entry(page)) {
@@ -479,22 +482,39 @@ void shmem_truncate_range(struct inode *
index++;
}
- if (partial) {
+ if (partial_start) {
struct page *page = NULL;
shmem_getpage(inode, start - 1, &page, SGP_READ, NULL);
if (page) {
- zero_user_segment(page, partial, PAGE_CACHE_SIZE);
+ unsigned int top = PAGE_CACHE_SIZE;
+ if (start > end) {
+ top = partial_end;
+ partial_end = 0;
+ }
+ zero_user_segment(page, partial_start, top);
set_page_dirty(page);
unlock_page(page);
page_cache_release(page);
}
}
+ if (partial_end) {
+ struct page *page = NULL;
+ shmem_getpage(inode, end, &page, SGP_READ, NULL);
+ if (page) {
+ zero_user_segment(page, 0, partial_end);
+ set_page_dirty(page);
+ unlock_page(page);
+ page_cache_release(page);
+ }
+ }
+ if (start >= end)
+ return;
index = start;
for ( ; ; ) {
cond_resched();
pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
- min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1,
+ min(end - index, (pgoff_t)PAGEVEC_SIZE),
pvec.pages, indices);
if (!pvec.nr) {
if (index == start)
@@ -502,7 +522,7 @@ void shmem_truncate_range(struct inode *
index = start;
continue;
}
- if (index == start && indices[0] > end) {
+ if (index == start && indices[0] >= end) {
shmem_deswap_pagevec(&pvec);
pagevec_release(&pvec);
break;
@@ -512,7 +532,7 @@ void shmem_truncate_range(struct inode *
struct page *page = pvec.pages[i];
index = indices[i];
- if (index > end)
+ if (index >= end)
break;
if (radix_tree_exceptional_entry(page)) {
@@ -1578,6 +1598,31 @@ static ssize_t shmem_file_splice_read(st
return error;
}
+static long shmem_fallocate(struct file *file, int mode, loff_t offset,
+ loff_t len)
+{
+ struct inode *inode = file->f_path.dentry->d_inode;
+ int error = -EOPNOTSUPP;
+
+ mutex_lock(&inode->i_mutex);
+
+ if (mode & FALLOC_FL_PUNCH_HOLE) {
+ struct address_space *mapping = file->f_mapping;
+ loff_t unmap_start = round_up(offset, PAGE_SIZE);
+ loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1;
+
+ if ((u64)unmap_end > (u64)unmap_start)
+ unmap_mapping_range(mapping, unmap_start,
+ 1 + unmap_end - unmap_start, 0);
+ shmem_truncate_range(inode, offset, offset + len - 1);
+ /* No need to unmap again: hole-punching leaves COWed pages */
+ error = 0;
+ }
+
+ mutex_unlock(&inode->i_mutex);
+ return error;
+}
+
static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
{
struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
@@ -2478,6 +2523,7 @@ static const struct file_operations shme
.fsync = noop_fsync,
.splice_read = shmem_file_splice_read,
.splice_write = generic_file_splice_write,
+ .fallocate = shmem_fallocate,
#endif
};
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2012-05-12 12:06 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-12 11:52 [PATCH 0/10] shmem/tmpfs: misc and fallocate Hugh Dickins
2012-05-12 11:59 ` [PATCH 1/10] shmem: replace page if mapping excludes its zone Hugh Dickins
2012-05-14 8:55 ` Cong Wang
2012-05-14 19:42 ` Hugh Dickins
2012-05-15 9:44 ` Cong Wang
2012-05-14 9:06 ` KAMEZAWA Hiroyuki
2012-05-14 23:13 ` Andrew Morton
2012-05-15 4:07 ` Hugh Dickins
2012-05-19 1:41 ` Hugh Dickins
2012-05-19 1:44 ` [PATCH v2 1/10] shmem: substitute " Hugh Dickins
2012-05-12 12:02 ` [PATCH 2/10] tmpfs: enable NOSEC optimization Hugh Dickins
2012-05-14 9:35 ` Cong Wang
2012-05-14 19:48 ` Hugh Dickins
2012-05-12 12:04 ` [PATCH 3/10] tmpfs: optimize clearing when writing Hugh Dickins
2012-05-15 8:51 ` Nick Piggin
2012-05-12 12:05 ` Hugh Dickins [this message]
2012-05-12 12:13 ` [PATCH 5/10] mm/fs: route MADV_REMOVE to FALLOC_FL_PUNCH_HOLE Hugh Dickins
2012-05-22 0:08 ` john stultz
2012-05-22 15:11 ` Hugh Dickins
2012-05-12 12:15 ` [PATCH 6/10] mm/fs: remove truncate_range Hugh Dickins
2012-05-12 12:17 ` [PATCH 7/10] tmpfs: support fallocate preallocation Hugh Dickins
2012-05-12 12:19 ` [PATCH 8/10] tmpfs: undo fallocation on failure Hugh Dickins
2012-05-12 12:21 ` [PATCH 9/10] tmpfs: quit when fallocate fills memory Hugh Dickins
2012-05-12 12:27 ` [PATCH 10/10] tmpfs: support SEEK_DATA and SEEK_HOLE Hugh Dickins
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=alpine.LSU.2.00.1205120504230.28861@eggly.anvils \
--to=hughd@google.com \
--cc=akpm@linux-foundation.org \
--cc=amwang@redhat.com \
--cc=hch@infradead.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox