diff options
Diffstat (limited to 'fs/ecryptfs/read_write.c')
| -rw-r--r-- | fs/ecryptfs/read_write.c | 27 |
1 files changed, 21 insertions, 6 deletions
diff --git a/fs/ecryptfs/read_write.c b/fs/ecryptfs/read_write.c index 6b7474a..948f576 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); |