From ecb5c8e1ebcb0c19b69a7d39eebb99fc5df5d6af Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Wed, 5 Sep 2012 15:48:23 +0200 Subject: [PATCH] udf: Fix data corruption for files in ICB When a file is stored in ICB (inode), we overwrite part of the file, and the page containing file's data is not in page cache, we end up corrupting file's data by overwriting them with zeros. The problem is we use simple_write_begin() which simply zeroes parts of the page which are not written to. The problem has been introduced by 2befc48a (udf: convert to new aops). Fix the problem by providing a ->write_begin function which makes the page properly uptodate. CC: # >= 2.6.24 Reported-by: Ian Abbott Signed-off-by: Jan Kara --- fs/udf/file.c | 35 +++++++++++++++++++++++++++++------ 1 file changed, 29 insertions(+), 6 deletions(-) diff --git a/fs/udf/file.c b/fs/udf/file.c index 7f3f7ba3df6e7..d1c6093fd3d3c 100644 --- a/fs/udf/file.c +++ b/fs/udf/file.c @@ -39,20 +39,24 @@ #include "udf_i.h" #include "udf_sb.h" -static int udf_adinicb_readpage(struct file *file, struct page *page) +static void __udf_adinicb_readpage(struct page *page) { struct inode *inode = page->mapping->host; char *kaddr; struct udf_inode_info *iinfo = UDF_I(inode); - BUG_ON(!PageLocked(page)); - kaddr = kmap(page); - memset(kaddr, 0, PAGE_CACHE_SIZE); memcpy(kaddr, iinfo->i_ext.i_data + iinfo->i_lenEAttr, inode->i_size); + memset(kaddr + inode->i_size, 0, PAGE_CACHE_SIZE - inode->i_size); flush_dcache_page(page); SetPageUptodate(page); kunmap(page); +} + +static int udf_adinicb_readpage(struct file *file, struct page *page) +{ + BUG_ON(!PageLocked(page)); + __udf_adinicb_readpage(page); unlock_page(page); return 0; @@ -77,6 +81,25 @@ static int udf_adinicb_writepage(struct page *page, return 0; } +static int udf_adinicb_write_begin(struct file *file, + struct address_space *mapping, loff_t pos, + unsigned len, unsigned flags, struct page **pagep, + void **fsdata) +{ + struct page *page; + + if (WARN_ON_ONCE(pos >= PAGE_CACHE_SIZE)) + return -EIO; + page = grab_cache_page_write_begin(mapping, 0, flags); + if (!page) + return -ENOMEM; + *pagep = page; + + if (!PageUptodate(page) && len != PAGE_CACHE_SIZE) + __udf_adinicb_readpage(page); + return 0; +} + static int udf_adinicb_write_end(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, unsigned copied, @@ -98,8 +121,8 @@ static int udf_adinicb_write_end(struct file *file, const struct address_space_operations udf_adinicb_aops = { .readpage = udf_adinicb_readpage, .writepage = udf_adinicb_writepage, - .write_begin = simple_write_begin, - .write_end = udf_adinicb_write_end, + .write_begin = udf_adinicb_write_begin, + .write_end = udf_adinicb_write_end, }; static ssize_t udf_file_aio_write(struct kiocb *iocb, const struct iovec *iov, -- 2.39.5