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author | Dr. Tilmann Bubeck <t.bubeck@reinform.de> | 2013-04-08 12:54:05 -0400 |
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committer | Theodore Ts'o <tytso@mit.edu> | 2013-04-08 12:54:05 -0400 |
commit | 393d1d1d76933886d5e1ce603214c9987589c6d5 (patch) | |
tree | 2f2368a9d787ccb8e69f61a3e5023ef9c4abfd8b /Documentation/filesystems/ext4.txt | |
parent | f78ee70db40040e6f38a5134527d4760254d6683 (diff) | |
download | linux-stable-393d1d1d76933886d5e1ce603214c9987589c6d5.tar.gz linux-stable-393d1d1d76933886d5e1ce603214c9987589c6d5.tar.bz2 linux-stable-393d1d1d76933886d5e1ce603214c9987589c6d5.zip |
ext4: implementation of a new ioctl called EXT4_IOC_SWAP_BOOT
Add a new ioctl, EXT4_IOC_SWAP_BOOT which swaps i_blocks and
associated attributes (like i_blocks, i_size, i_flags, ...) from the
specified inode with inode EXT4_BOOT_LOADER_INO (#5). This is
typically used to store a boot loader in a secure part of the
filesystem, where it can't be changed by a normal user by accident.
The data blocks of the previous boot loader will be associated with
the given inode.
This usercode program is a simple example of the usage:
int main(int argc, char *argv[])
{
int fd;
int err;
if ( argc != 2 ) {
printf("usage: ext4-swap-boot-inode FILE-TO-SWAP\n");
exit(1);
}
fd = open(argv[1], O_WRONLY);
if ( fd < 0 ) {
perror("open");
exit(1);
}
err = ioctl(fd, EXT4_IOC_SWAP_BOOT);
if ( err < 0 ) {
perror("ioctl");
exit(1);
}
close(fd);
exit(0);
}
[ Modified by Theodore Ts'o to fix a number of bugs in the original code.]
Signed-off-by: Dr. Tilmann Bubeck <t.bubeck@reinform.de>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Diffstat (limited to 'Documentation/filesystems/ext4.txt')
-rw-r--r-- | Documentation/filesystems/ext4.txt | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt index 34ea4f1fa6ea..5dd957d8b25b 100644 --- a/Documentation/filesystems/ext4.txt +++ b/Documentation/filesystems/ext4.txt @@ -587,6 +587,16 @@ Table of Ext4 specific ioctls bitmaps and inode table, the userspace tool thus just passes the new number of blocks. +EXT4_IOC_SWAP_BOOT Swap i_blocks and associated attributes + (like i_blocks, i_size, i_flags, ...) from + the specified inode with inode + EXT4_BOOT_LOADER_INO (#5). This is typically + used to store a boot loader in a secure part of + the filesystem, where it can't be changed by a + normal user by accident. + The data blocks of the previous boot loader + will be associated with the given inode. + .............................................................................. References |