[BUG] Calling BTRFS_IOC_TREE_SEARCH for a non existant key
Hi all,
I discovered that when I call the BTRFS_IOC_TREE_SEARCH ioctl for a not
existent key, the ioctl requires a lot of time to be completed.
I tracks down the problem in the function search_ioctl(). It seems that the
function btrfs_search_forward() doesn't check if key is greater than max_key.
file ioctl.c
988 static noinline int search_ioctl(struct inode *inode,
989 struct btrfs_ioctl_search_args *args)
[...]
1025 while(1) {
1026 ret = btrfs_search_forward(root, key, max_key, path,
0,
1027 sk-min_transid);
1028 if (ret != 0) {
1029 if (ret 0)
1030 ret = 0;
1031 goto err;
1032 }
1033 ret = copy_to_sk(root, path, key, sk, args-buf,
1034 sk_offset, num_found);
1035 btrfs_release_path(root, path);
1036 if (ret || num_found = sk-nr_items)
1037 break;
1038 }
The function btrfs_search_forward() doesn't check the key (or min_key) against
max_key when the parameter cache_only == 0.
from ctree.c
3624 int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key
*min_key,
3625 struct btrfs_key *max_key,
3626 struct btrfs_path *path, int cache_only,
3627 u64 min_trans)
3628 {
[..]
3678 if (!cache_only)
3679 break;
3680 if (max_key) {
3681 btrfs_node_key(cur, disk_key, slot);
3682 if (comp_keys(disk_key, max_key) =
0) {
3683 ret = 1;
3684 goto out;
3685 }
3686 }
So in the function search_ioctl the search is not completed until the args
buffer is filled or the function copy_to_sk detects that key is greater than
sk-max_*.
However the check performed by the function copy_to_sk is not always
sufficient to detect if a key is greater than sk-max_*. For example if
key.objectid sk-max_objectid but key.offset is sk-max_offset, the key is
supposed to be valid.
913 static noinline int copy_to_sk(struct btrfs_root *root,
[...]
970 }
971 advance_key:
972 ret = 0;
973 if (key-offset (u64)-1 key-offset sk-max_offset)
974 key-offset++;
975 else if (key-type (u8)-1 key-type sk-max_type) {
976 key-offset = 0;
977 key-type++;
978 } else if (key-objectid (u64)-1 key-objectid sk-
max_objectid) {
979 key-offset = 0;
980 key-type = 0;
981 key-objectid++;
982 } else
983 ret = 1;
984 overflow:
985 *num_found += found;
986 return ret;
987 }
To solve this problem it should be sufficient a key check before the call of
btrfs_search_forward().
But I don't know if this is a workaround or the root cause is inside the
function btrfs_search_forward() that doesn't check the key against max_key if
cached_only is 0.
Regards
G.Baroncelli
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[PATCH] Improve error handling in filesystem df
The return values of ioctl weren't being printed to stderr on failure,
causing the command to silently fail, resulting in a very confused
user.
Signed-off-by: Ben Gamari bgamari.f...@gmail.com
---
btrfs_cmds.c |2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/btrfs_cmds.c b/btrfs_cmds.c
index 8031c58..45da2bd 100644
--- a/btrfs_cmds.c
+++ b/btrfs_cmds.c
@@ -857,6 +857,7 @@ int do_df_filesystem(int nargs, char **argv)
ret = ioctl(fd, BTRFS_IOC_SPACE_INFO, sargs);
if (ret) {
+ fprintf(stderr, ERROR: can't query '%s' for free space
(%s)\n, path, strerror(-ret));
free(sargs);
return ret;
}
@@ -875,6 +876,7 @@ int do_df_filesystem(int nargs, char **argv)
ret = ioctl(fd, BTRFS_IOC_SPACE_INFO, sargs);
if (ret) {
+ fprintf(stderr, ERROR: can't query '%s' for free space
(%s)\n, path, strerror(-ret));
free(sargs);
return ret;
}
--
1.7.1
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Re: [BUG?] There is a possibility that 'i_ino' overflows
(2010/12/16 17:44), Tsutomu Itoh wrote:
Hi,
In btrfs, inode number is increased each time a new file or directory
is made.
Therefore, if the making deletion of the file is repeated, value of
'i_ino' increases rapidly.
For example, inode number changes as follows.
$ touch foo
$ ls -i foo
266 foo
$ rm foo
$ touch bar
$ ls -i bar
267 bar
$
And then, length of 'i_ino' and 'objectid' is as follows on the x86
system.
unsigned long i_ino == 32bits
u64 objectid== 64bits
Therefore, in the operation to substitute 'objectid' to 'i_ino',
'i_ino' overflows when 'objectid' 4294967296 is substituted to 'i_ino'.
Then, the file with inode number 0 is made.
I think that it is better to recycle inode number that became unused.
And, at least, I think that it should make the filesystem not become an
abnormal condition.
This patch is a patch that makes an error when inode number is bigger
than BTRFS_LAST_FREE_OBJECTID.
Signed-off-by: Tsutomu Itoh t-i...@jp.fujitsu.com
---
inode.c |4
1 file changed, 4 insertions(+)
diff -urNp linux-2.6.37-rc6/fs/btrfs/inode.c
linux-2.6.37-rc6.new/fs/btrfs/inode.c
--- linux-2.6.37-rc6/fs/btrfs/inode.c 2010-12-16 10:24:48.0 +0900
+++ linux-2.6.37-rc6.new/fs/btrfs/inode.c 2010-12-20 09:04:18.0
+0900
@@ -4529,6 +4529,10 @@ static struct inode *btrfs_new_inode(str
inode_init_owner(inode, dir, mode);
inode-i_ino = objectid;
+ if (unlikely(inode-i_ino (unsigned long)BTRFS_LAST_FREE_OBJECTID)) {
+ ret = -ENOSPC;
+ goto fail;
+ }
inode_set_bytes(inode, 0);
inode-i_mtime = inode-i_atime = inode-i_ctime = CURRENT_TIME;
inode_item = btrfs_item_ptr(path-nodes[0], path-slots[0],
As a result, ls command has looped infinitely, and btrfsck detected the
error.
Please see below.
$ uname -a
Linux luna 2.6.37-rc5 #1 SMP Thu Dec 9 13:02:41 JST 2010 i686 i686 i386
GNU/Linux
$ df -T /test1
FilesystemType 1K-blocks Used Available Use% Mounted on
/dev/sdd14 btrfs 416256056 3717632 1% /test1
$ strace -FfTttx ls /test1
14:03:10.115440 execve(/bin/ls, [ls, /test1], [/* 28 vars */]) = 0
0.000181
...
...
14:03:10.123431 stat(/test1, {st_mode=S_IFDIR|0777, st_size=8, ...}) = 0
0.17
14:03:10.123521 open(/test1, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC) =
3 0.18
14:03:10.123578 fcntl(3, F_GETFD) = 0x1 (flags FD_CLOEXEC) 0.13
14:03:10.123637 getdents(3, /* 3 entries */, 32768) = 72 0.25
14:03:10.123712 getdents(3, /* 1 entries */, 32768) = 24 0.16
14:03:10.123768 getdents(3, /* 1 entries */, 32768) = 24 0.15
14:03:10.123824 getdents(3, /* 1 entries */, 32768) = 24 0.15
14:03:10.123880 getdents(3, /* 1 entries */, 32768) = 24 0.15
14:03:10.123936 getdents(3, /* 1 entries */, 32768) = 24 0.14
14:03:10.123992 getdents(3, /* 1 entries */, 32768) = 24 0.15
14:03:10.124047 getdents(3, /* 1 entries */, 32768) = 24 0.15
14:03:10.124103 getdents(3, /* 1 entries */, 32768) = 24 0.15
14:03:10.124261 getdents(3, /* 1 entries */, 32768) = 24 0.16
14:03:10.124320 getdents(3, /* 1 entries */, 32768) = 24 0.15
14:03:10.124381 getdents(3, /* 1 entries */, 32768) = 24 0.15
14:03:10.124437 getdents(3, /* 1 entries */, 32768) = 24 0.14
14:03:10.124493 getdents(3, /* 1 entries */, 32768) = 24 0.14
14:03:10.124549 getdents(3, /* 1 entries */, 32768) = 24 0.14
14:03:10.124605 getdents(3, /* 1 entries */, 32768) = 24 0.14
14:03:10.124661 getdents(3, /* 1 entries */, 32768) = 24 0.14
14:03:10.124717 getdents(3, /* 1 entries */, 32768) = 24 0.14
14:03:10.124773 getdents(3, /* 1 entries */, 32768) = 24 0.14
14:03:10.124840 getdents(3, /* 1 entries */, 32768) = 24 0.14
14:03:10.124896 getdents(3, /* 1 entries */, 32768) = 24 0.14
...
...
$ cd /test1
$ ls -i A123
ls: cannot access A123: No such file or directory
$ touch
$ ls -i
1
$
# umount /test1
# btrfsck /dev/sdd14
root 5 inode 0 errors 2001
unresolved ref dir 256 index 4294967041 namelen 4 name A123
filetype 1 error 4
root 5 inode 1 errors 2001
unresolved ref dir 256 index 4294967042 namelen 4 name
filetype 1 error 4
root 5 inode 4294967296 errors 2000
unresolved ref dir 256 index 4294967041 namelen 4 name A123
filetype 0 error 3
root 5 inode 4294967297 errors 2000
unresolved ref dir 256 index 4294967042 namelen 4 name
filetype 0 error 3
found 28672 bytes used err is 1
total csum bytes: 0
total tree bytes: 28672
total fs tree bytes: 8192
btree space waste bytes: 23191
file data blocks allocated: 0
referenced 0
Btrfs v0.19-36-g70c6c10
#
Regards,
Itoh
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