2:27 p.m.
----- Original Message -----
At 2012-3-10 5:50, Dave Anderson wrote:
>
> It's failing in its call to get_pathname(). I haven't had a chance to
You are right. I forgot to check every call to get_pathname. The new
patch has fixed the problem of swap.
Although the patch appears to work in the simple cases that I have tested,
I have a few issues with it.
First, the get_pathname() function prototype is -- and has always been -- this:
void get_pathname(ulong dentry, char *pathname, int length, int full, ulong vfsmnt)
where the "vfsmnt" argument has always been a struct vfsmount pointer.
With your patch, prior to making get_pathname() calls, you typically
make a VALID_STRUCT(mount) call first, and if true, you modify the
vfsmnt argument to be a struct mount pointer.
It would make more sense maintenance-wise, and would simplify the patch,
if the get_pathname() "vfsmnt" argument would continue to be a struct
vfsmount pointer. And at the top of get_pathname(), you could make the
adjustments for when it is embedded inside a struct mount.
For example, taking these patches to open_files_dump() and file_dump():
@@ -2226,12 +2299,16 @@ open_files_dump(ulong task, int flags, struct reference *ref)
if (VALID_MEMBER(fs_struct_rootmnt)) {
vfsmnt = ULONG(fs_struct_buf +
OFFSET(fs_struct_rootmnt));
+ if (VALID_STRUCT(mount))
+ vfsmnt = vfsmnt - OFFSET(mount_mnt);
get_pathname(root_dentry, root_pathname,
BUFSIZE, 1, vfsmnt);
} else if (use_path) {
vfsmnt = ULONG(fs_struct_buf +
OFFSET(fs_struct_root) +
OFFSET(path_mnt));
+ if (VALID_STRUCT(mount))
+ vfsmnt = vfsmnt - OFFSET(mount_mnt);
get_pathname(root_dentry, root_pathname,
BUFSIZE, 1, vfsmnt);
} else {
@@ -2250,12 +2327,16 @@ open_files_dump(ulong task, int flags, struct reference *ref)
if (VALID_MEMBER(fs_struct_pwdmnt)) {
vfsmnt = ULONG(fs_struct_buf +
OFFSET(fs_struct_pwdmnt));
+ if (VALID_STRUCT(mount))
+ vfsmnt = vfsmnt - OFFSET(mount_mnt);
get_pathname(pwd_dentry, pwd_pathname,
BUFSIZE, 1, vfsmnt);
} else if (use_path) {
vfsmnt = ULONG(fs_struct_buf +
OFFSET(fs_struct_pwd) +
OFFSET(path_mnt));
+ if (VALID_STRUCT(mount))
+ vfsmnt = vfsmnt - OFFSET(mount_mnt);
get_pathname(pwd_dentry, pwd_pathname,
BUFSIZE, 1, vfsmnt);
@@ -2686,7 +2767,12 @@ file_dump(ulong file, ulong dentry, ulong inode, int fd, int
flags)
if (flags & DUMP_FULL_NAME) {
if (VALID_MEMBER(file_f_vfsmnt)) {
vfsmnt = get_root_vfsmount(file_buf);
- get_pathname(dentry, pathname, BUFSIZE, 1, vfsmnt);
+ if (VALID_STRUCT(mount))
+ get_pathname(dentry, pathname, BUFSIZE, 1,
+ vfsmnt - OFFSET(mount_mnt));
+ else
+ get_pathname(dentry, pathname, BUFSIZE, 1,
+ vfsmnt);
if (STRNEQ(pathname, "/pts/") &&
STREQ(vfsmount_devname(vfsmnt, buf1, BUFSIZE),
"devpts"))
If the vfsmount-to-mount calculation were always done in get_pathname() itself,
then the patches above would be unnecessary. The same is true for a few other
parts of the patch.
Did you consider doing it that way?
And consider the following patched version of display_dentry_info() below.
The two get_pathname() calls below would generate fatal errors on older
kernels because OFFSET(mount_mnt) will be invalid:
if (!found && symbol_exists("pipe_mnt")) {
get_symbol_data("pipe_mnt", sizeof(long), &vfs);
if (VALID_STRUCT(mount))
readmem(vfs - OFFSET(mount_mnt), KVADDR, mount_buf,
SIZE(mount),
"mount buffer", FAULT_ON_ERROR);
else
readmem(vfs, KVADDR, vfsmount_buf, SIZE(vfsmount),
"vfsmount buffer", FAULT_ON_ERROR);
sb = ULONG(vfsmount_buf + OFFSET(vfsmount_mnt_sb));
if (superblock && (sb == superblock)) {
get_pathname(dentry, pathname, BUFSIZE, 1,
vfs - OFFSET(mount_mnt));
found = TRUE;
}
}
if (!found && symbol_exists("sock_mnt")) {
get_symbol_data("sock_mnt", sizeof(long), &vfs);
if (VALID_STRUCT(mount))
readmem(vfs - OFFSET(mount_mnt), KVADDR, mount_buf,
SIZE(mount),
"mount buffer", FAULT_ON_ERROR);
else
readmem(vfs, KVADDR, vfsmount_buf, SIZE(vfsmount),
"vfsmount buffer", FAULT_ON_ERROR);
sb = ULONG(vfsmount_buf + OFFSET(vfsmount_mnt_sb));
if (superblock && (sb == superblock)) {
get_pathname(dentry, pathname, BUFSIZE, 1,
vfs - OFFSET(mount_mnt));
found = TRUE;
}
}
If we can continue to have get_pathname() receive a vfsmount pointer,
it reduces the chance of introducing new bugs like the above, and future
maintenance will be easier.
Comments?
Dave