From 02fac1297eb3f471a27368271aadd285548297b0 Mon Sep 17 00:00:00 2001 From: Allison Henderson Date: Tue, 6 Sep 2011 21:53:01 -0400 Subject: [PATCH] ext4: fix partial page writes While running extended fsx tests to verify the preceeding patches, a similar bug was also found in the write operation When ever a write operation begins or ends in a hole, or extends EOF, the partial page contained in the hole or beyond EOF needs to be zeroed out. To correct this the new ext4_discard_partial_page_buffers_no_lock routine is used to zero out the partial page, but only for buffer heads that are already unmapped. Signed-off-by: Allison Henderson Signed-off-by: "Theodore Ts'o" --- fs/ext4/inode.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index f86b149fb8b1..6ecc93979e48 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -2255,6 +2255,7 @@ static int ext4_da_write_begin(struct file *file, struct address_space *mapping, pgoff_t index; struct inode *inode = mapping->host; handle_t *handle; + loff_t page_len; index = pos >> PAGE_CACHE_SHIFT; @@ -2301,6 +2302,13 @@ retry: */ if (pos + len > inode->i_size) ext4_truncate_failed_write(inode); + } else { + page_len = pos & (PAGE_CACHE_SIZE - 1); + if (page_len > 0) { + ret = ext4_discard_partial_page_buffers_no_lock(handle, + inode, page, pos - page_len, page_len, + EXT4_DISCARD_PARTIAL_PG_ZERO_UNMAPPED); + } } if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries)) @@ -2343,6 +2351,7 @@ static int ext4_da_write_end(struct file *file, loff_t new_i_size; unsigned long start, end; int write_mode = (int)(unsigned long)fsdata; + loff_t page_len; if (write_mode == FALL_BACK_TO_NONDELALLOC) { if (ext4_should_order_data(inode)) { @@ -2391,6 +2400,16 @@ static int ext4_da_write_end(struct file *file, } ret2 = generic_write_end(file, mapping, pos, len, copied, page, fsdata); + + page_len = PAGE_CACHE_SIZE - + ((pos + copied - 1) & (PAGE_CACHE_SIZE - 1)); + + if (page_len > 0) { + ret = ext4_discard_partial_page_buffers_no_lock(handle, + inode, page, pos + copied - 1, page_len, + EXT4_DISCARD_PARTIAL_PG_ZERO_UNMAPPED); + } + copied = ret2; if (ret2 < 0) ret = ret2; -- 2.30.2