ext4: store maxbytes for bitmapped files and return EFBIG as appropriate
Calculate & store the max offset for bitmapped files, and
catch too-large seeks, truncates, and writes in ext4, shortening
or rejecting as appropriate.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 1a81cd6..a6b2aa1 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -56,8 +56,25 @@
ssize_t ret;
int err;
- ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
+ /*
+ * If we have encountered a bitmap-format file, the size limit
+ * is smaller than s_maxbytes, which is for extent-mapped files.
+ */
+ if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)) {
+ struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+ size_t length = iov_length(iov, nr_segs);
+
+ if (pos > sbi->s_bitmap_maxbytes)
+ return -EFBIG;
+
+ if (pos + length > sbi->s_bitmap_maxbytes) {
+ nr_segs = iov_shorten((struct iovec *)iov, nr_segs,
+ sbi->s_bitmap_maxbytes - pos);
+ }
+ }
+
+ ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
/*
* Skip flushing if there was an error, or if nothing was written.
*/
