Re: [Crash-utility] [PATCH] fix command vm/files -d/mount on new kernel

----- 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 -- Crash-utility mailing list Crash-utility(a)redhat.com https://www.redhat.com/mailman/listinfo/crash-utility