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Wed, 18 Dec 2019 11:15:47 -0800 (PST) X-Google-Smtp-Source: APXvYqxoq1DKGgFPtnMGhoAJMtcbciDkEMQytNX8AvkNkVK8lsW2C3r+w7lObZV7/fv72rv4hWG2JYKDz2uChLbujCg= X-Received: by 2002:aca:dd43:: with SMTP id u64mr1215556oig.101.1576696547536; Wed, 18 Dec 2019 11:15:47 -0800 (PST) MIME-Version: 1.0 References: <20191218130935.32402-1-agruenba@redhat.com> <20191218185216.GA7497@magnolia> In-Reply-To: <20191218185216.GA7497@magnolia> From: Andreas Gruenbacher Date: Wed, 18 Dec 2019 20:15:36 +0100 Message-ID: To: "Darrick J. Wong" X-MC-Unique: yhNx6gW9NyGGbpz5Uca9QQ-1 X-Mimecast-Spam-Score: 0 X-Headers-End: 1iheng-006326-4U Subject: Re: [f2fs-dev] [PATCH v3] fs: Fix page_mkwrite off-by-one errors X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jan Kara , Adrian Hunter , Chris Mason , Andreas Dilger , Sage Weil , Richard Weinberger , Christoph Hellwig , Ilya Dryomov , linux-ext4 , Josef Bacik , Alexander Viro , David Sterba , Jaegeuk Kim , Ceph Development , Theodore Ts'o , Artem Bityutskiy , Jeff Layton , LKML , linux-f2fs-devel@lists.sourceforge.net, linux-xfs@vger.kernel.org, linux-fsdevel , linux-mtd@lists.infradead.org, Linus Torvalds , linux-btrfs@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On Wed, Dec 18, 2019 at 7:55 PM Darrick J. Wong wrote: > On Wed, Dec 18, 2019 at 02:09:35PM +0100, Andreas Gruenbacher wrote: > > Hi Darrick, > > > > can this fix go in via the xfs tree? > > Er, I'd rather not touch five other filesystems via the XFS tree. > However, a more immediate problem that I think I see is... > > > Thanks, > > Andreas > > > > -- > > > > The check in block_page_mkwrite that is meant to determine whether an > > offset is within the inode size is off by one. This bug has been copied > > into iomap_page_mkwrite and several filesystems (ubifs, ext4, f2fs, > > ceph). > > > > Fix that by introducing a new page_mkwrite_check_truncate helper that > > checks for truncate and computes the bytes in the page up to EOF. Use > > the helper in the above mentioned filesystems. > > > > In addition, use the new helper in btrfs as well. > > > > Signed-off-by: Andreas Gruenbacher > > Acked-by: David Sterba (btrfs part) > > Acked-by: Richard Weinberger (ubifs part) > > --- > > fs/btrfs/inode.c | 15 ++++----------- > > fs/buffer.c | 16 +++------------- > > fs/ceph/addr.c | 2 +- > > fs/ext4/inode.c | 14 ++++---------- > > fs/f2fs/file.c | 19 +++++++------------ > > fs/iomap/buffered-io.c | 18 +++++------------- > > fs/ubifs/file.c | 3 +-- > > include/linux/pagemap.h | 28 ++++++++++++++++++++++++++++ > > 8 files changed, 53 insertions(+), 62 deletions(-) > > > > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > > index 56032c518b26..86c6fcd8139d 100644 > > --- a/fs/btrfs/inode.c > > +++ b/fs/btrfs/inode.c > > @@ -9016,13 +9016,11 @@ vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf) > > ret = VM_FAULT_NOPAGE; /* make the VM retry the fault */ > > again: > > lock_page(page); > > - size = i_size_read(inode); > > > > - if ((page->mapping != inode->i_mapping) || > > - (page_start >= size)) { > > - /* page got truncated out from underneath us */ > > + ret2 = page_mkwrite_check_truncate(page, inode); > > + if (ret2 < 0) > > goto out_unlock; > > ...here we try to return -EFAULT as vm_fault_t. Notice how btrfs returns > VM_FAULT_* values directly and never calls block_page_mkwrite_return? I > know dsterba acked this, but I cannot see how this is correct? Well, page_mkwrite_check_truncate can only fail with -EFAULT, in which case btrfs_page_mkwrite will return VM_FAULT_NOPAGE. It would be cleaner not to discard page_mkwrite_check_truncate's return value though. > > - } > > + zero_start = ret2; > > wait_on_page_writeback(page); > > > > lock_extent_bits(io_tree, page_start, page_end, &cached_state); > > @@ -9043,6 +9041,7 @@ vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf) > > goto again; > > } > > > > + size = i_size_read(inode); > > if (page->index == ((size - 1) >> PAGE_SHIFT)) { > > reserved_space = round_up(size - page_start, > > fs_info->sectorsize); > > @@ -9075,12 +9074,6 @@ vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf) > > } > > ret2 = 0; > > > > - /* page is wholly or partially inside EOF */ > > - if (page_start + PAGE_SIZE > size) > > - zero_start = offset_in_page(size); > > - else > > - zero_start = PAGE_SIZE; > > - > > if (zero_start != PAGE_SIZE) { > > kaddr = kmap(page); > > memset(kaddr + zero_start, 0, PAGE_SIZE - zero_start); > > diff --git a/fs/buffer.c b/fs/buffer.c > > index d8c7242426bb..53aabde57ca7 100644 > > --- a/fs/buffer.c > > +++ b/fs/buffer.c > > @@ -2499,23 +2499,13 @@ int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, > > struct page *page = vmf->page; > > struct inode *inode = file_inode(vma->vm_file); > > unsigned long end; > > - loff_t size; > > int ret; > > > > lock_page(page); > > - size = i_size_read(inode); > > - if ((page->mapping != inode->i_mapping) || > > - (page_offset(page) > size)) { > > - /* We overload EFAULT to mean page got truncated */ > > - ret = -EFAULT; > > + ret = page_mkwrite_check_truncate(page, inode); > > + if (ret < 0) > > goto out_unlock; > > - } > > - > > - /* page is wholly or partially inside EOF */ > > - if (((page->index + 1) << PAGE_SHIFT) > size) > > - end = size & ~PAGE_MASK; > > - else > > - end = PAGE_SIZE; > > + end = ret; > > > > ret = __block_write_begin(page, 0, end, get_block); > > if (!ret) > > diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c > > index 7ab616601141..ef958aa4adb4 100644 > > --- a/fs/ceph/addr.c > > +++ b/fs/ceph/addr.c > > @@ -1575,7 +1575,7 @@ static vm_fault_t ceph_page_mkwrite(struct vm_fault *vmf) > > do { > > lock_page(page); > > > > - if ((off > size) || (page->mapping != inode->i_mapping)) { > > + if (page_mkwrite_check_truncate(page, inode) < 0) { > > unlock_page(page); > > ret = VM_FAULT_NOPAGE; > > break; > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > > index 28f28de0c1b6..51ab1d2cac80 100644 > > --- a/fs/ext4/inode.c > > +++ b/fs/ext4/inode.c > > @@ -5871,7 +5871,6 @@ vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf) > > { > > struct vm_area_struct *vma = vmf->vma; > > struct page *page = vmf->page; > > - loff_t size; > > unsigned long len; > > int err; > > vm_fault_t ret; > > @@ -5907,18 +5906,13 @@ vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf) > > } > > > > lock_page(page); > > - size = i_size_read(inode); > > - /* Page got truncated from under us? */ > > - if (page->mapping != mapping || page_offset(page) > size) { > > + err = page_mkwrite_check_truncate(page, inode); > > + if (err < 0) { > > unlock_page(page); > > - ret = VM_FAULT_NOPAGE; > > - goto out; > > + goto out_ret; > > } > > + len = err; > > > > - if (page->index == size >> PAGE_SHIFT) > > - len = size & ~PAGE_MASK; > > - else > > - len = PAGE_SIZE; > > /* > > * Return if we have all the buffers mapped. This avoids the need to do > > * journal_start/journal_stop which can block and take a long time > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > > index 85af112e868d..0e77b2e6f873 100644 > > --- a/fs/f2fs/file.c > > +++ b/fs/f2fs/file.c > > @@ -51,7 +51,7 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) > > struct inode *inode = file_inode(vmf->vma->vm_file); > > struct f2fs_sb_info *sbi = F2FS_I_SB(inode); > > struct dnode_of_data dn = { .node_changed = false }; > > - int err; > > + int offset, err; > > > > if (unlikely(f2fs_cp_error(sbi))) { > > err = -EIO; > > @@ -70,13 +70,14 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) > > file_update_time(vmf->vma->vm_file); > > down_read(&F2FS_I(inode)->i_mmap_sem); > > lock_page(page); > > - if (unlikely(page->mapping != inode->i_mapping || > > - page_offset(page) > i_size_read(inode) || > > - !PageUptodate(page))) { > > + err = -EFAULT; > > + if (likely(PageUptodate(page))) > > + err = page_mkwrite_check_truncate(page, inode); > > + if (unlikely(err < 0)) { > > unlock_page(page); > > - err = -EFAULT; > > goto out_sem; > > } > > + offset = err; > > > > /* block allocation */ > > __do_map_lock(sbi, F2FS_GET_BLOCK_PRE_AIO, true); > > @@ -101,14 +102,8 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) > > if (PageMappedToDisk(page)) > > goto out_sem; > > > > - /* page is wholly or partially inside EOF */ > > - if (((loff_t)(page->index + 1) << PAGE_SHIFT) > > > - i_size_read(inode)) { > > - loff_t offset; > > - > > - offset = i_size_read(inode) & ~PAGE_MASK; > > + if (offset != PAGE_SIZE) > > zero_user_segment(page, offset, PAGE_SIZE); > > - } > > set_page_dirty(page); > > if (!PageUptodate(page)) > > SetPageUptodate(page); > > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > > index d33c7bc5ee92..1aaf157fd6e9 100644 > > --- a/fs/iomap/buffered-io.c > > +++ b/fs/iomap/buffered-io.c > > @@ -1062,24 +1062,16 @@ vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops) > > struct page *page = vmf->page; > > struct inode *inode = file_inode(vmf->vma->vm_file); > > unsigned long length; > > - loff_t offset, size; > > + loff_t offset; > > ssize_t ret; > > > > lock_page(page); > > - size = i_size_read(inode); > > - offset = page_offset(page); > > - if (page->mapping != inode->i_mapping || offset > size) { > > - /* We overload EFAULT to mean page got truncated */ > > - ret = -EFAULT; > > + ret = page_mkwrite_check_truncate(page, inode); > > + if (ret < 0) > > goto out_unlock; > > - } > > - > > - /* page is wholly or partially inside EOF */ > > - if (offset > size - PAGE_SIZE) > > - length = offset_in_page(size); > > - else > > - length = PAGE_SIZE; > > + length = ret; > > > > + offset = page_offset(page); > > while (length > 0) { > > ret = iomap_apply(inode, offset, length, > > IOMAP_WRITE | IOMAP_FAULT, ops, page, > > diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c > > index cd52585c8f4f..91f7a1f2db0d 100644 > > --- a/fs/ubifs/file.c > > +++ b/fs/ubifs/file.c > > @@ -1563,8 +1563,7 @@ static vm_fault_t ubifs_vm_page_mkwrite(struct vm_fault *vmf) > > } > > > > lock_page(page); > > - if (unlikely(page->mapping != inode->i_mapping || > > - page_offset(page) > i_size_read(inode))) { > > + if (unlikely(page_mkwrite_check_truncate(page, inode) < 0)) { > > /* Page got truncated out from underneath us */ > > goto sigbus; > > } > > diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h > > index 37a4d9e32cd3..ccb14b6a16b5 100644 > > --- a/include/linux/pagemap.h > > +++ b/include/linux/pagemap.h > > @@ -636,4 +636,32 @@ static inline unsigned long dir_pages(struct inode *inode) > > PAGE_SHIFT; > > } > > > > +/** > > + * page_mkwrite_check_truncate - check if page was truncated > > + * @page: the page to check > > + * @inode: the inode to check the page against > > + * > > + * Returns the number of bytes in the page up to EOF, > > + * or -EFAULT if the page was truncated. > > + */ > > +static inline int page_mkwrite_check_truncate(struct page *page, > > + struct inode *inode) > > +{ > > + loff_t size = i_size_read(inode); > > + pgoff_t index = size >> PAGE_SHIFT; > > + int offset = offset_in_page(size); > > + > > + if (page->mapping != inode->i_mapping) > > + return -EFAULT; > > + > > + /* page is wholly inside EOF */ > > + if (page->index < index) > > + return PAGE_SIZE; > > + /* page is wholly past EOF */ > > + if (page->index > index || !offset) > > + return -EFAULT; > > + /* page is partially inside EOF */ > > + return offset; > > +} > > + > > #endif /* _LINUX_PAGEMAP_H */ > > -- > > 2.20.1 > > > _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel