Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755357Ab2ELMGK (ORCPT ); Sat, 12 May 2012 08:06:10 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:44181 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754807Ab2ELMGH (ORCPT ); Sat, 12 May 2012 08:06:07 -0400 Date: Sat, 12 May 2012 05:05:51 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@eggly.anvils To: Andrew Morton cc: Christoph Hellwig , Cong Wang , 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 In-Reply-To: Message-ID: References: User-Agent: Alpine 2.00 (LSU 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5299 Lines: 168 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 Signed-off-by: Hugh Dickins --- 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 #include #include +#include #include #include #include @@ -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 from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/