From 240e2df5c740d73fc08cac9989872212deb2d20e Mon Sep 17 00:00:00 2001 From: Michael Halcrow Date: Wed, 27 Jun 2007 14:09:44 -0700 Subject: eCryptfs: fix write zeros behavior This patch fixes the processes involved in wiping regions of the data during truncate and write events, fixing a kernel hang in 2.6.22-rc4 while assuring that zero values are written out to the appropriate locations during events in which the i_size will change. The range passed to ecryptfs_truncate() from ecryptfs_prepare_write() includes the page that is the object of ecryptfs_prepare_write(). This leads to a kernel hang as read_cache_page() is executed on the same page in the ecryptfs_truncate() execution path. This patch remedies this by limiting the range passed to ecryptfs_truncate() so as to exclude the page that is the object of ecryptfs_prepare_write(); it also adds code to ecryptfs_prepare_write() to zero out the region of its own page when writing past the i_size position. This patch also modifies ecryptfs_truncate() so that when a file is truncated to a smaller size, eCryptfs will zero out the contents of the new last page from the new size through to the end of the last page. Signed-off-by: Michael Halcrow Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/ecryptfs/mmap.c | 53 +++++++++++++++++++++++++++++------------------------ 1 file changed, 29 insertions(+), 24 deletions(-) (limited to 'fs/ecryptfs/mmap.c') diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c index 55cec98a84e..6df410c7726 100644 --- a/fs/ecryptfs/mmap.c +++ b/fs/ecryptfs/mmap.c @@ -56,9 +56,6 @@ static struct page *ecryptfs_get1page(struct file *file, int index) return read_mapping_page(mapping, index, (void *)file); } -static -int write_zeros(struct file *file, pgoff_t index, int start, int num_zeros); - /** * ecryptfs_fill_zeros * @file: The ecryptfs file @@ -101,10 +98,13 @@ int ecryptfs_fill_zeros(struct file *file, loff_t new_length) if (old_end_page_index == new_end_page_index) { /* Start and end are in the same page; we just need to * set a portion of the existing page to zero's */ - rc = write_zeros(file, index, (old_end_pos_in_page + 1), - (new_end_pos_in_page - old_end_pos_in_page)); + rc = ecryptfs_write_zeros(file, index, + (old_end_pos_in_page + 1), + (new_end_pos_in_page + - old_end_pos_in_page)); if (rc) - ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], " + ecryptfs_printk(KERN_ERR, "ecryptfs_write_zeros(" + "file=[%p], " "index=[0x%.16x], " "old_end_pos_in_page=[d], " "(PAGE_CACHE_SIZE - new_end_pos_in_page" @@ -117,10 +117,10 @@ int ecryptfs_fill_zeros(struct file *file, loff_t new_length) goto out; } /* Fill the remainder of the previous last page with zeros */ - rc = write_zeros(file, index, (old_end_pos_in_page + 1), + rc = ecryptfs_write_zeros(file, index, (old_end_pos_in_page + 1), ((PAGE_CACHE_SIZE - 1) - old_end_pos_in_page)); if (rc) { - ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], " + ecryptfs_printk(KERN_ERR, "ecryptfs_write_zeros(file=[%p], " "index=[0x%.16x], old_end_pos_in_page=[d], " "(PAGE_CACHE_SIZE - old_end_pos_in_page)=[d]) " "returned [%d]\n", file, index, @@ -131,9 +131,10 @@ int ecryptfs_fill_zeros(struct file *file, loff_t new_length) index++; while (index < new_end_page_index) { /* Fill all intermediate pages with zeros */ - rc = write_zeros(file, index, 0, PAGE_CACHE_SIZE); + rc = ecryptfs_write_zeros(file, index, 0, PAGE_CACHE_SIZE); if (rc) { - ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], " + ecryptfs_printk(KERN_ERR, "ecryptfs_write_zeros(" + "file=[%p], " "index=[0x%.16x], " "old_end_pos_in_page=[d], " "(PAGE_CACHE_SIZE - new_end_pos_in_page" @@ -149,9 +150,9 @@ int ecryptfs_fill_zeros(struct file *file, loff_t new_length) } /* Fill the portion at the beginning of the last new page with * zero's */ - rc = write_zeros(file, index, 0, (new_end_pos_in_page + 1)); + rc = ecryptfs_write_zeros(file, index, 0, (new_end_pos_in_page + 1)); if (rc) { - ecryptfs_printk(KERN_ERR, "write_zeros(file=" + ecryptfs_printk(KERN_ERR, "ecryptfs_write_zeros(file=" "[%p], index=[0x%.16x], 0, " "new_end_pos_in_page=[%d]" "returned [%d]\n", file, index, @@ -400,7 +401,6 @@ out: static int ecryptfs_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to) { - loff_t pos; int rc = 0; if (from == 0 && to == PAGE_CACHE_SIZE) @@ -408,14 +408,19 @@ static int ecryptfs_prepare_write(struct file *file, struct page *page, up to date. */ if (!PageUptodate(page)) rc = ecryptfs_do_readpage(file, page, page->index); - pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; - if (pos > i_size_read(page->mapping->host)) { - rc = ecryptfs_truncate(file->f_path.dentry, pos); - if (rc) { - printk(KERN_ERR "Error on attempt to " - "truncate to (higher) offset [%lld];" - " rc = [%d]\n", pos, rc); - goto out; + if (page->index != 0) { + loff_t end_of_prev_pg_pos = + (((loff_t)page->index << PAGE_CACHE_SHIFT) - 1); + + if (end_of_prev_pg_pos > i_size_read(page->mapping->host)) { + rc = ecryptfs_truncate(file->f_path.dentry, + end_of_prev_pg_pos); + if (rc) { + printk(KERN_ERR "Error on attempt to " + "truncate to (higher) offset [%lld];" + " rc = [%d]\n", end_of_prev_pg_pos, rc); + goto out; + } } } out: @@ -753,7 +758,7 @@ out: } /** - * write_zeros + * ecryptfs_write_zeros * @file: The ecryptfs file * @index: The index in which we are writing * @start: The position after the last block of data @@ -763,8 +768,8 @@ out: * * (start + num_zeros) must be less than or equal to PAGE_CACHE_SIZE */ -static -int write_zeros(struct file *file, pgoff_t index, int start, int num_zeros) +int +ecryptfs_write_zeros(struct file *file, pgoff_t index, int start, int num_zeros) { int rc = 0; struct page *tmp_page; -- cgit v1.2.3