From 3665d0e58fa44f50c744f85c7e8ad21d5b10e206 Mon Sep 17 00:00:00 2001
From: Badari Pulavarty <pbadari@us.ibm.com>
Date: Fri, 8 Sep 2006 09:48:21 -0700
Subject: [PATCH] [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()
<c01c5140> ext3_getblk+0x98/0x2a6 <c03b2806> md_wakeup_thread+0x26/0x2a
<c01c536d> ext3_bread+0x1f/0x88 <c01cedf9> ext3_quota_read+0x136/0x1ae
<c018b683> v1_read_dqblk+0x61/0xac <c0188f32> dquot_acquire+0xf6/0x107
<c01ceaba> ext3_acquire_dquot+0x46/0x68 <c01897d4> dqget+0x155/0x1e7
<c018a97b> dquot_transfer+0x3e0/0x3e9 <c016fe52> dput+0x23/0x13e
<c01c7986> ext3_setattr+0xc3/0x240 <c0120f66> current_fs_time+0x52/0x6a
<c017320e> notify_change+0x2bd/0x30d <c0159246> chown_common+0x9c/0xc5
<c02a222c> strncpy_from_user+0x3b/0x68 <c0167fe6> do_path_lookup+0xdf/0x266
<c016841b> __user_walk_fd+0x44/0x5a <c01592b9> sys_chown+0x4a/0x55
<c015a43c> vfs_write+0xe7/0x13c <c01695d4> sys_mkdir+0x1f/0x23
<c0102a97> 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 <pbadari@us.ibm.com>
Acked-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
fs/ext3/inode.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
index c5ee9f0691e3b..0f0b1eadb98dd 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)) {
--
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