From: Badari Pulavarty Date: Fri, 8 Sep 2006 16:48:21 +0000 (-0700) Subject: [PATCH] ext3_getblk() should handle HOLE correctly X-Git-Tag: v2.6.18-rc7~20 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3665d0e58fa44f50c744f85c7e8ad21d5b10e206;p=linux-2.6 [PATCH] ext3_getblk() should handle HOLE correctly It has been reported that ext3_getblk() is not doing the right thing and triggering following WARN(): BUG: warning at fs/ext3/inode.c:1016/ext3_getblk() ext3_getblk+0x98/0x2a6 md_wakeup_thread+0x26/0x2a ext3_bread+0x1f/0x88 ext3_quota_read+0x136/0x1ae v1_read_dqblk+0x61/0xac dquot_acquire+0xf6/0x107 ext3_acquire_dquot+0x46/0x68 dqget+0x155/0x1e7 dquot_transfer+0x3e0/0x3e9 dput+0x23/0x13e ext3_setattr+0xc3/0x240 current_fs_time+0x52/0x6a notify_change+0x2bd/0x30d chown_common+0x9c/0xc5 strncpy_from_user+0x3b/0x68 do_path_lookup+0xdf/0x266 __user_walk_fd+0x44/0x5a sys_chown+0x4a/0x55 vfs_write+0xe7/0x13c sys_mkdir+0x1f/0x23 syscall_call+0x7/0xb Looking at the code, it looks like it's not handle HOLE correctly. It ends up returning -EIO. Here is the patch to fix it. If we really want to be paranoid, we can allow return values 0 (HOLE), 1 (we asked for one block) and return -EIO for more than 1 block. But I really don't see a reason for doing it - all we need is the block# here. (doesn't matter how many blocks are mapped). ext3_get_blocks_handle() returns number of blocks it mapped. It returns 0 in case of HOLE. ext3_getblk() should handle HOLE properly (currently its dumping warning stack and returning -EIO). Signed-off-by: Badari Pulavarty Acked-by: Mingming Cao Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c index c5ee9f0691..0f0b1eadb9 100644 --- a/fs/ext3/inode.c +++ b/fs/ext3/inode.c @@ -1009,11 +1009,14 @@ struct buffer_head *ext3_getblk(handle_t *handle, struct inode *inode, buffer_trace_init(&dummy.b_history); err = ext3_get_blocks_handle(handle, inode, block, 1, &dummy, create, 1); - if (err == 1) { + /* + * ext3_get_blocks_handle() returns number of blocks + * mapped. 0 in case of a HOLE. + */ + if (err > 0) { + if (err > 1) + WARN_ON(1); err = 0; - } else if (err >= 0) { - WARN_ON(1); - err = -EIO; } *errp = err; if (!err && buffer_mapped(&dummy)) {