From: Eric Sandeen Date: Tue, 18 Dec 2007 00:20:10 +0000 (-0800) Subject: ecryptfs: fix fsx data corruption problems X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=7a3f595cc8298df14a7c71b0d876bafd8e9e1cbf;p=GitHub%2Fexynos8895%2Fandroid_kernel_samsung_universal8895.git ecryptfs: fix fsx data corruption problems ecryptfs in 2.6.24-rc3 wasn't surviving fsx for me at all, dying after 4 ops. Generally, encountering problems with stale data and improperly zeroed pages. An extending truncate + write for example would expose stale data. With the changes below I got to a million ops and beyond with all mmap ops disabled - mmap still needs work. (A version of this patch on a RHEL5 kernel ran for over 110 million fsx ops) I added a few comments as well, to the best of my understanding as I read through the code. Signed-off-by: Eric Sandeen Acked-by: Michael Halcrow Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c index 16a7a555f392..32c5711d79a3 100644 --- a/fs/ecryptfs/mmap.c +++ b/fs/ecryptfs/mmap.c @@ -263,14 +263,13 @@ out: return 0; } +/* This function must zero any hole we create */ static int ecryptfs_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to) { int rc = 0; + loff_t prev_page_end_size; - if (from == 0 && to == PAGE_CACHE_SIZE) - goto out; /* If we are writing a full page, it will be - up to date. */ if (!PageUptodate(page)) { rc = ecryptfs_read_lower_page_segment(page, page->index, 0, PAGE_CACHE_SIZE, @@ -283,22 +282,32 @@ static int ecryptfs_prepare_write(struct file *file, struct page *page, } else SetPageUptodate(page); } - 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)) { + prev_page_end_size = ((loff_t)page->index << PAGE_CACHE_SHIFT); + + /* + * If creating a page or more of holes, zero them out via truncate. + * Note, this will increase i_size. + */ + if (page->index != 0) { + if (prev_page_end_size > i_size_read(page->mapping->host)) { rc = ecryptfs_truncate(file->f_path.dentry, - end_of_prev_pg_pos); + prev_page_end_size); if (rc) { printk(KERN_ERR "Error on attempt to " "truncate to (higher) offset [%lld];" - " rc = [%d]\n", end_of_prev_pg_pos, rc); + " rc = [%d]\n", prev_page_end_size, rc); goto out; } } - if (end_of_prev_pg_pos + 1 > i_size_read(page->mapping->host)) - zero_user_page(page, 0, PAGE_CACHE_SIZE, KM_USER0); + } + /* + * Writing to a new page, and creating a small hole from start of page? + * Zero it out. + */ + if ((i_size_read(page->mapping->host) == prev_page_end_size) && + (from != 0)) { + zero_user_page(page, 0, PAGE_CACHE_SIZE, KM_USER0); } out: return rc; diff --git a/fs/ecryptfs/read_write.c b/fs/ecryptfs/read_write.c index 6b7474a4336a..948f57624c05 100644 --- a/fs/ecryptfs/read_write.c +++ b/fs/ecryptfs/read_write.c @@ -124,6 +124,10 @@ int ecryptfs_write(struct file *ecryptfs_file, char *data, loff_t offset, loff_t pos; int rc = 0; + /* + * if we are writing beyond current size, then start pos + * at the current size - we'll fill in zeros from there. + */ if (offset > ecryptfs_file_size) pos = ecryptfs_file_size; else @@ -137,6 +141,7 @@ int ecryptfs_write(struct file *ecryptfs_file, char *data, loff_t offset, if (num_bytes > total_remaining_bytes) num_bytes = total_remaining_bytes; if (pos < offset) { + /* remaining zeros to write, up to destination offset */ size_t total_remaining_zeros = (offset - pos); if (num_bytes > total_remaining_zeros) @@ -167,17 +172,27 @@ int ecryptfs_write(struct file *ecryptfs_file, char *data, loff_t offset, } } ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0); + + /* + * pos: where we're now writing, offset: where the request was + * If current pos is before request, we are filling zeros + * If we are at or beyond request, we are writing the *data* + * If we're in a fresh page beyond eof, zero it in either case + */ + if (pos < offset || !start_offset_in_page) { + /* We are extending past the previous end of the file. + * Fill in zero values to the end of the page */ + memset(((char *)ecryptfs_page_virt + + start_offset_in_page), 0, + PAGE_CACHE_SIZE - start_offset_in_page); + } + + /* pos >= offset, we are now writing the data request */ if (pos >= offset) { memcpy(((char *)ecryptfs_page_virt + start_offset_in_page), (data + data_offset), num_bytes); data_offset += num_bytes; - } else { - /* We are extending past the previous end of the file. - * Fill in zero values up to the start of where we - * will be writing data. */ - memset(((char *)ecryptfs_page_virt - + start_offset_in_page), 0, num_bytes); } kunmap_atomic(ecryptfs_page_virt, KM_USER0); flush_dcache_page(ecryptfs_page);