Re: [PATCH v2 2/2] f2fs: introduce DATA_GENERIC_ENHANCE

From: Chao Yu
Date: Wed Apr 24 2019 - 11:06:48 EST

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On 2019-4-24 17:36, Jaegeuk Kim wrote:
> On 04/15, Chao Yu wrote:
>> Previously, f2fs_is_valid_blkaddr(, blkaddr, DATA_GENERIC) will check
>> whether @blkaddr locates in main area or not.
>>
>> That check is weak, since the block address in range of main area can
>> point to the address which is not valid in segment info table, and we
>> can not detect such condition, we may suffer worse corruption as system
>> continues running.
>>
>> So this patch introduce DATA_GENERIC_ENHANCE to enhance the sanity check
>> which trigger SIT bitmap check rather than only range check.
>>
>> This patch did below changes as wel:
>> - set SBI_NEED_FSCK in f2fs_is_valid_blkaddr().
>> - get rid of is_valid_data_blkaddr() to avoid panic if blkaddr is invalid.
>> - introduce verify_fio_blkaddr() to wrap fio {new,old}_blkaddr validation check.
>> - spread blkaddr check in:
>> * f2fs_get_node_info()
>> * __read_out_blkaddrs()
>> * f2fs_submit_page_read()
>> * ra_data_block()
>> * do_recover_data()
>>
>> This patch can fix bug reported from bugzilla below:
>>
>> https://bugzilla.kernel.org/show_bug.cgi?id=203215
>> https://bugzilla.kernel.org/show_bug.cgi?id=203223
>> https://bugzilla.kernel.org/show_bug.cgi?id=203231
>> https://bugzilla.kernel.org/show_bug.cgi?id=203235
>> https://bugzilla.kernel.org/show_bug.cgi?id=203241
>
> Hi Chao,
>
> This introduces failures on xfstests/generic/446, and I'm testing the below
> patch on top of this. Could you check this patch, so that I could combine
> both of them?
>
> From 8c1808c1743ad75d1ad8d1dc5a53910edaf7afd7 Mon Sep 17 00:00:00 2001
> From: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> Date: Wed, 24 Apr 2019 00:21:07 +0100
> Subject: [PATCH] f2fs: consider data race on read and truncation on
> DATA_GENERIC_ENHANCE
>
> DATA_GENERIC_ENHANCE enhanced to validate block addresses on read/write paths.
> But, xfstest/generic/446 compalins some generated kernel messages saying invalid
> bitmap was detected when reading a block. The reaons is, when we get the
> block addresses from extent_cache, there is no lock to synchronize it from
> truncating the blocks in parallel.
>
> This patch tries to return EFAULT without warning and setting SBI_NEED_FSCK
> in this case.
>
> Fixes: ("f2fs: introduce DATA_GENERIC_ENHANCE")
> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> ---
> fs/f2fs/checkpoint.c | 35 ++++++++++++++++++-----------------
> fs/f2fs/data.c | 25 ++++++++++++++++++-------
> fs/f2fs/f2fs.h | 6 ++++++
> fs/f2fs/gc.c | 9 ++++++---
> 4 files changed, 48 insertions(+), 27 deletions(-)
>
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index e37fbbf843a5..805a33088e82 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -130,26 +130,28 @@ struct page *f2fs_get_tmp_page(struct f2fs_sb_info *sbi, pgoff_t index)
> return __get_meta_page(sbi, index, false);
> }
>
> -static bool __is_bitmap_valid(struct f2fs_sb_info *sbi, block_t blkaddr)
> +static bool __is_bitmap_valid(struct f2fs_sb_info *sbi, block_t blkaddr,
> + int type)
> {
> struct seg_entry *se;
> unsigned int segno, offset;
> bool exist;
>
> + if (type != DATA_GENERIC_ENHANCE && type != DATA_GENERIC_ENHANCE_READ)
> + return true;
> +
> segno = GET_SEGNO(sbi, blkaddr);
> offset = GET_BLKOFF_FROM_SEG0(sbi, blkaddr);
> se = get_seg_entry(sbi, segno);
>
> exist = f2fs_test_bit(offset, se->cur_valid_map);
> -
> - if (!exist) {
> + if (!exist && type == DATA_GENERIC_ENHANCE) {
> f2fs_msg(sbi->sb, KERN_ERR, "Inconsistent error "
> "blkaddr:%u, sit bitmap:%d", blkaddr, exist);
> set_sbi_flag(sbi, SBI_NEED_FSCK);
> WARN_ON(1);
> - return false;
> }
> - return true;
> + return exist;
> }
>
> bool f2fs_is_valid_blkaddr(struct f2fs_sb_info *sbi,
> @@ -173,23 +175,22 @@ bool f2fs_is_valid_blkaddr(struct f2fs_sb_info *sbi,
> return false;
> break;
> case META_POR:
> + if (unlikely(blkaddr >= MAX_BLKADDR(sbi) ||
> + blkaddr < MAIN_BLKADDR(sbi)))
> + return false;
> + break;
> case DATA_GENERIC:
> case DATA_GENERIC_ENHANCE:
> + case DATA_GENERIC_ENHANCE_READ:
> if (unlikely(blkaddr >= MAX_BLKADDR(sbi) ||
> - blkaddr < MAIN_BLKADDR(sbi))) {
> - if (type == DATA_GENERIC ||
> - type == DATA_GENERIC_ENHANCE) {
> - f2fs_msg(sbi->sb, KERN_WARNING,
> - "access invalid blkaddr:%u", blkaddr);
> - set_sbi_flag(sbi, SBI_NEED_FSCK);
> - WARN_ON(1);
> - }
> + blkaddr < MAIN_BLKADDR(sbi))) {
> + f2fs_msg(sbi->sb, KERN_WARNING,
> + "access invalid blkaddr:%u", blkaddr);
> + set_sbi_flag(sbi, SBI_NEED_FSCK);
> + WARN_ON(1);
> return false;
> } else {
> - if (type == DATA_GENERIC_ENHANCE) {
> - if (!__is_bitmap_valid(sbi, blkaddr))
> - return false;
> - }
> + return __is_bitmap_valid(sbi, blkaddr, type);
> }
> break;
> case META_GENERIC:
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 34d248ac9e0f..d32a82f25f5a 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -564,9 +564,6 @@ static struct bio *f2fs_grab_read_bio(struct inode *inode, block_t blkaddr,
> struct bio_post_read_ctx *ctx;
> unsigned int post_read_steps = 0;
>
> - if (!f2fs_is_valid_blkaddr(sbi, blkaddr, DATA_GENERIC_ENHANCE))
> - return ERR_PTR(-EFAULT);
> -
> bio = f2fs_bio_alloc(sbi, min_t(int, nr_pages, BIO_MAX_PAGES), false);
> if (!bio)
> return ERR_PTR(-ENOMEM);
> @@ -597,9 +594,6 @@ static int f2fs_submit_page_read(struct inode *inode, struct page *page,
> struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
> struct bio *bio;
>
> - if (!f2fs_is_valid_blkaddr(sbi, blkaddr, DATA_GENERIC_ENHANCE))
> - return -EFAULT;
> -
> bio = f2fs_grab_read_bio(inode, blkaddr, 1, 0);
> if (IS_ERR(bio))
> return PTR_ERR(bio);
> @@ -741,6 +735,11 @@ struct page *f2fs_get_read_data_page(struct inode *inode, pgoff_t index,
>
> if (f2fs_lookup_extent_cache(inode, index, &ei)) {
> dn.data_blkaddr = ei.blk + index - ei.fofs;
> + if (!f2fs_is_valid_blkaddr(F2FS_I_SB(inode), dn.data_blkaddr,
> + DATA_GENERIC_ENHANCE_READ)) {

If I'm not missing anything, we just need use DATA_GENERIC_ENHANCE_READ to cover
below two paths:
- gc_data_segment -> f2fs_get_read_data_page
- move_data_page -> f2fs_get_lock_data_page -> f2fs_get_read_data_page

Other paths which calls f2fs_get_read_data_page is safe to verify blkaddr with
DATA_GENERIC_ENHANCE?

> + err = -EFAULT;
> + goto put_err;
> + }
> goto got_it;
> }
>
> @@ -754,6 +753,13 @@ struct page *f2fs_get_read_data_page(struct inode *inode, pgoff_t index,
> err = -ENOENT;
> goto put_err;
> }
> + if (dn.data_blkaddr != NEW_ADDR &&
> + !f2fs_is_valid_blkaddr(F2FS_I_SB(inode),
> + dn.data_blkaddr,
> + DATA_GENERIC_ENHANCE)) {
> + err = -EFAULT;
> + goto put_err;
> + }
> got_it:
> if (PageUptodate(page)) {
> unlock_page(page);
> @@ -1566,7 +1572,7 @@ static int f2fs_read_single_page(struct inode *inode, struct page *page,
> }
>
> if (!f2fs_is_valid_blkaddr(F2FS_I_SB(inode), block_nr,
> - DATA_GENERIC_ENHANCE)) {
> + DATA_GENERIC_ENHANCE_READ)) {
> ret = -EFAULT;
> goto out;
> }
> @@ -2528,6 +2534,11 @@ static int f2fs_write_begin(struct file *file, struct address_space *mapping,
> zero_user_segment(page, 0, PAGE_SIZE);
> SetPageUptodate(page);
> } else {
> + if (!f2fs_is_valid_blkaddr(sbi, blkaddr,
> + DATA_GENERIC_ENHANCE_READ)) {

Need DATA_GENERIC_ENHANCE because write() is exclusive with truncate() due to
inode_lock()?

Thanks,

> + err = -EFAULT;
> + goto fail;
> + }
> err = f2fs_submit_page_read(inode, page, blkaddr);
> if (err)
> goto fail;
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index f5ffc09705eb..533fafca68f4 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -212,6 +212,12 @@ enum {
> META_POR,
> DATA_GENERIC, /* check range only */
> DATA_GENERIC_ENHANCE, /* strong check on range and segment bitmap */
> + DATA_GENERIC_ENHANCE_READ, /*
> + * strong check on range and segment
> + * bitmap but no warning due to race
> + * condition of read on truncated area
> + * by extent_cache
> + */
> META_GENERIC,
> };
>
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index 3a097949b5d4..963fb4571fd9 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -656,6 +656,11 @@ static int ra_data_block(struct inode *inode, pgoff_t index)
>
> if (f2fs_lookup_extent_cache(inode, index, &ei)) {
> dn.data_blkaddr = ei.blk + index - ei.fofs;
> + if (unlikely(!f2fs_is_valid_blkaddr(sbi, dn.data_blkaddr,
> + DATA_GENERIC_ENHANCE_READ))) {
> + err = -EFAULT;
> + goto put_page;
> + }
> goto got_it;
> }
>
> @@ -669,14 +674,12 @@ static int ra_data_block(struct inode *inode, pgoff_t index)
> err = -ENOENT;
> goto put_page;
> }
> -
> -got_it:
> if (unlikely(!f2fs_is_valid_blkaddr(sbi, dn.data_blkaddr,
> DATA_GENERIC_ENHANCE))) {
> err = -EFAULT;
> goto put_page;
> }
> -
> +got_it:
> /* read page */
> fio.page = page;
> fio.new_blkaddr = fio.old_blkaddr = dn.data_blkaddr;
>

Next message: Christoph Hellwig: "Re: [PATCH v2 RFC/RFT 1/5] ARM: dma-mapping: Add fallback normal page allocations"
Previous message: Mathieu Desnoyers: "Re: [PATCH 1/4] glibc: Perform rseq(2) registration at C startup and thread creation (v7)"
In reply to: Jaegeuk Kim: "Re: [PATCH v2 2/2] f2fs: introduce DATA_GENERIC_ENHANCE"
Next in thread: Jaegeuk Kim: "Re: [PATCH v2 2/2] f2fs: introduce DATA_GENERIC_ENHANCE"
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