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Message-ID: <CAHJ8P3JXJfX=YVKGuQzM6n+yRbAh6Kxem+dLqdP_3F_BN=b_+Q@mail.gmail.com>
Date: Thu, 5 Jun 2025 09:15:29 +0800
From: Zhiguo Niu <niuzhiguo84@...il.com>
To: Chao Yu <chao@...nel.org>
Cc: jaegeuk@...nel.org, stable@...nel.org, linux-kernel@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH v2] f2fs: fix to zero post-eof page
Chao Yu via Linux-f2fs-devel <linux-f2fs-devel@...ts.sourceforge.net>
于2025年6月4日周三 17:01写道：
>
> fstest reports a f2fs bug:
>
> generic/363 42s ... [failed, exit status 1]- output mismatch (see /share/git/fstests/results//generic/363.out.bad)
> --- tests/generic/363.out 2025-01-12 21:57:40.271440542 +0800
> +++ /share/git/fstests/results//generic/363.out.bad 2025-05-19 19:55:58.000000000 +0800
> @@ -1,2 +1,78 @@
> QA output created by 363
> fsx -q -S 0 -e 1 -N 100000
> +READ BAD DATA: offset = 0xd6fb, size = 0xf044, fname = /mnt/f2fs/junk
> +OFFSET GOOD BAD RANGE
> +0x1540d 0x0000 0x2a25 0x0
> +operation# (mod 256) for the bad data may be 37
> +0x1540e 0x0000 0x2527 0x1
> ...
> (Run 'diff -u /share/git/fstests/tests/generic/363.out /share/git/fstests/results//generic/363.out.bad' to see the entire diff)
> Ran: generic/363
> Failures: generic/363
> Failed 1 of 1 tests
>
> The root cause is user can update post-eof page via mmap, however, f2fs missed
> to zero post-eof page in below operations, so, once it expands i_size, then it
> will include dummy data locates previous post-eof page, so during below
> operations, we need to zero post-eof page.
>
> Operations which can include dummy data after previous i_size after expanding
> i_size:
> - write
> - mapwrite
> - truncate
> - fallocate
> * preallocate
> * zero_range
> * insert_range
> * collapse_range
> - clone_range (doesn’t support in f2fs)
> - copy_range (doesn’t support in f2fs)
>
> Cc: stable@...nel.org
> Signed-off-by: Chao Yu <chao@...nel.org>
> ---
> v2:
> - cover f2fs_zero_post_eof_page w/ invalidate_lock
> fs/f2fs/file.c | 38 ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 38 insertions(+)
>
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 6bd3de64f2a8..ee5e662d2a4c 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -35,6 +35,17 @@
> #include <trace/events/f2fs.h>
> #include <uapi/linux/f2fs.h>
>
> +static void f2fs_zero_post_eof_page(struct inode *inode, loff_t new_size)
> +{
> + loff_t old_size = i_size_read(inode);
> +
> + if (old_size > new_size)
Hi Chao,
should it be old_size >= new_size?
> + return;
> +
> + /* zero or drop pages only in range of [old_size, new_size] */
> + truncate_pagecache(inode, old_size);
> +}
> +
> static vm_fault_t f2fs_filemap_fault(struct vm_fault *vmf)
> {
> struct inode *inode = file_inode(vmf->vma->vm_file);
> @@ -103,8 +114,13 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf)
>
> f2fs_bug_on(sbi, f2fs_has_inline_data(inode));
>
> + filemap_invalidate_lock(inode->i_mapping);
> + f2fs_zero_post_eof_page(inode, (folio->index + 1) << PAGE_SHIFT);
> + filemap_invalidate_unlock(inode->i_mapping);
> +
> file_update_time(vmf->vma->vm_file);
> filemap_invalidate_lock_shared(inode->i_mapping);
> +
> folio_lock(folio);
> if (unlikely(folio->mapping != inode->i_mapping ||
> folio_pos(folio) > i_size_read(inode) ||
> @@ -1109,6 +1125,8 @@ int f2fs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
> f2fs_down_write(&fi->i_gc_rwsem[WRITE]);
> filemap_invalidate_lock(inode->i_mapping);
>
> + if (attr->ia_size > old_size)
> + f2fs_zero_post_eof_page(inode, old_size);
I'm a little suspicious about the logic here， here old_size is from
i_size_read(inode),
and it will compare with the "old_size" in f2fs_zero_post_eof_page, it
is also from i_size_read(inode),
so is this actually meaningless?
Thanks!
> truncate_setsize(inode, attr->ia_size);
>
> if (attr->ia_size <= old_size)
> @@ -1227,6 +1245,10 @@ static int f2fs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
> if (ret)
> return ret;
>
> + filemap_invalidate_lock(inode->i_mapping);
> + f2fs_zero_post_eof_page(inode, offset + len);
> + filemap_invalidate_unlock(inode->i_mapping);
> +
> pg_start = ((unsigned long long) offset) >> PAGE_SHIFT;
> pg_end = ((unsigned long long) offset + len) >> PAGE_SHIFT;
>
> @@ -1510,6 +1532,8 @@ static int f2fs_do_collapse(struct inode *inode, loff_t offset, loff_t len)
> f2fs_down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
> filemap_invalidate_lock(inode->i_mapping);
>
> + f2fs_zero_post_eof_page(inode, offset + len);
> +
> f2fs_lock_op(sbi);
> f2fs_drop_extent_tree(inode);
> truncate_pagecache(inode, offset);
> @@ -1631,6 +1655,10 @@ static int f2fs_zero_range(struct inode *inode, loff_t offset, loff_t len,
> if (ret)
> return ret;
>
> + filemap_invalidate_lock(mapping);
> + f2fs_zero_post_eof_page(inode, offset + len);
> + filemap_invalidate_unlock(mapping);
> +
> pg_start = ((unsigned long long) offset) >> PAGE_SHIFT;
> pg_end = ((unsigned long long) offset + len) >> PAGE_SHIFT;
>
> @@ -1762,6 +1790,8 @@ static int f2fs_insert_range(struct inode *inode, loff_t offset, loff_t len)
> /* avoid gc operation during block exchange */
> f2fs_down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
> filemap_invalidate_lock(mapping);
> +
> + f2fs_zero_post_eof_page(inode, offset + len);
> truncate_pagecache(inode, offset);
>
> while (!ret && idx > pg_start) {
> @@ -1819,6 +1849,10 @@ static int f2fs_expand_inode_data(struct inode *inode, loff_t offset,
> if (err)
> return err;
>
> + filemap_invalidate_lock(inode->i_mapping);
> + f2fs_zero_post_eof_page(inode, offset + len);
> + filemap_invalidate_unlock(inode->i_mapping);
> +
> f2fs_balance_fs(sbi, true);
>
> pg_start = ((unsigned long long)offset) >> PAGE_SHIFT;
> @@ -4860,6 +4894,10 @@ static ssize_t f2fs_write_checks(struct kiocb *iocb, struct iov_iter *from)
> err = file_modified(file);
> if (err)
> return err;
> +
> + filemap_invalidate_lock(inode->i_mapping);
> + f2fs_zero_post_eof_page(inode, iocb->ki_pos + iov_iter_count(from));
> + filemap_invalidate_unlock(inode->i_mapping);
> return count;
> }
>
> --
> 2.49.0
>
>
>
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> Linux-f2fs-devel mailing list
> Linux-f2fs-devel@...ts.sourceforge.net
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