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authorDr. Tilmann Bubeck <t.bubeck@reinform.de>2013-04-08 12:54:05 -0400
committerTheodore Ts'o <tytso@mit.edu>2013-04-08 12:54:05 -0400
commit393d1d1d76933886d5e1ce603214c9987589c6d5 (patch)
tree2f2368a9d787ccb8e69f61a3e5023ef9c4abfd8b /fs/ext4/move_extent.c
parentf78ee70db40040e6f38a5134527d4760254d6683 (diff)
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 'fs/ext4/move_extent.c')
-rw-r--r--fs/ext4/move_extent.c48
1 files changed, 25 insertions, 23 deletions
diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index 33e1c086858b..a2e696e16331 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -144,12 +144,13 @@ mext_next_extent(struct inode *inode, struct ext4_ext_path *path,
}
/**
- * double_down_write_data_sem - Acquire two inodes' write lock of i_data_sem
+ * ext4_double_down_write_data_sem - Acquire two inodes' write lock
+ * of i_data_sem
*
* Acquire write lock of i_data_sem of the two inodes
*/
-static void
-double_down_write_data_sem(struct inode *first, struct inode *second)
+void
+ext4_double_down_write_data_sem(struct inode *first, struct inode *second)
{
if (first < second) {
down_write(&EXT4_I(first)->i_data_sem);
@@ -162,14 +163,15 @@ double_down_write_data_sem(struct inode *first, struct inode *second)
}
/**
- * double_up_write_data_sem - Release two inodes' write lock of i_data_sem
+ * ext4_double_up_write_data_sem - Release two inodes' write lock of i_data_sem
*
* @orig_inode: original inode structure to be released its lock first
* @donor_inode: donor inode structure to be released its lock second
* Release write lock of i_data_sem of two inodes (orig and donor).
*/
-static void
-double_up_write_data_sem(struct inode *orig_inode, struct inode *donor_inode)
+void
+ext4_double_up_write_data_sem(struct inode *orig_inode,
+ struct inode *donor_inode)
{
up_write(&EXT4_I(orig_inode)->i_data_sem);
up_write(&EXT4_I(donor_inode)->i_data_sem);
@@ -976,7 +978,7 @@ again:
* necessary, just swap data blocks between orig and donor.
*/
if (uninit) {
- double_down_write_data_sem(orig_inode, donor_inode);
+ ext4_double_down_write_data_sem(orig_inode, donor_inode);
/* If any of extents in range became initialized we have to
* fallback to data copying */
uninit = mext_check_coverage(orig_inode, orig_blk_offset,
@@ -990,7 +992,7 @@ again:
goto drop_data_sem;
if (!uninit) {
- double_up_write_data_sem(orig_inode, donor_inode);
+ ext4_double_up_write_data_sem(orig_inode, donor_inode);
goto data_copy;
}
if ((page_has_private(pagep[0]) &&
@@ -1004,7 +1006,7 @@ again:
donor_inode, orig_blk_offset,
block_len_in_page, err);
drop_data_sem:
- double_up_write_data_sem(orig_inode, donor_inode);
+ ext4_double_up_write_data_sem(orig_inode, donor_inode);
goto unlock_pages;
}
data_copy:
@@ -1065,11 +1067,11 @@ repair_branches:
* Extents are swapped already, but we are not able to copy data.
* Try to swap extents to it's original places
*/
- double_down_write_data_sem(orig_inode, donor_inode);
+ ext4_double_down_write_data_sem(orig_inode, donor_inode);
replaced_count = mext_replace_branches(handle, donor_inode, orig_inode,
orig_blk_offset,
block_len_in_page, &err2);
- double_up_write_data_sem(orig_inode, donor_inode);
+ ext4_double_up_write_data_sem(orig_inode, donor_inode);
if (replaced_count != block_len_in_page) {
EXT4_ERROR_INODE_BLOCK(orig_inode, (sector_t)(orig_blk_offset),
"Unable to copy data block,"
@@ -1209,15 +1211,15 @@ mext_check_arguments(struct inode *orig_inode,
}
/**
- * mext_inode_double_lock - Lock i_mutex on both @inode1 and @inode2
+ * ext4_inode_double_lock - Lock i_mutex on both @inode1 and @inode2
*
* @inode1: the inode structure
* @inode2: the inode structure
*
* Lock two inodes' i_mutex
*/
-static void
-mext_inode_double_lock(struct inode *inode1, struct inode *inode2)
+void
+ext4_inode_double_lock(struct inode *inode1, struct inode *inode2)
{
BUG_ON(inode1 == inode2);
if (inode1 < inode2) {
@@ -1230,15 +1232,15 @@ mext_inode_double_lock(struct inode *inode1, struct inode *inode2)
}
/**
- * mext_inode_double_unlock - Release i_mutex on both @inode1 and @inode2
+ * ext4_inode_double_unlock - Release i_mutex on both @inode1 and @inode2
*
* @inode1: the inode that is released first
* @inode2: the inode that is released second
*
*/
-static void
-mext_inode_double_unlock(struct inode *inode1, struct inode *inode2)
+void
+ext4_inode_double_unlock(struct inode *inode1, struct inode *inode2)
{
mutex_unlock(&inode1->i_mutex);
mutex_unlock(&inode2->i_mutex);
@@ -1333,7 +1335,7 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp,
return -EINVAL;
}
/* Protect orig and donor inodes against a truncate */
- mext_inode_double_lock(orig_inode, donor_inode);
+ ext4_inode_double_lock(orig_inode, donor_inode);
/* Wait for all existing dio workers */
ext4_inode_block_unlocked_dio(orig_inode);
@@ -1342,7 +1344,7 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp,
inode_dio_wait(donor_inode);
/* Protect extent tree against block allocations via delalloc */
- double_down_write_data_sem(orig_inode, donor_inode);
+ ext4_double_down_write_data_sem(orig_inode, donor_inode);
/* Check the filesystem environment whether move_extent can be done */
ret = mext_check_arguments(orig_inode, donor_inode, orig_start,
donor_start, &len);
@@ -1466,7 +1468,7 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp,
* b. racing with ->readpage, ->write_begin, and ext4_get_block
* in move_extent_per_page
*/
- double_up_write_data_sem(orig_inode, donor_inode);
+ ext4_double_up_write_data_sem(orig_inode, donor_inode);
while (orig_page_offset <= seq_end_page) {
@@ -1500,7 +1502,7 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp,
block_len_in_page = rest_blocks;
}
- double_down_write_data_sem(orig_inode, donor_inode);
+ ext4_double_down_write_data_sem(orig_inode, donor_inode);
if (ret < 0)
break;
@@ -1538,10 +1540,10 @@ out:
ext4_ext_drop_refs(holecheck_path);
kfree(holecheck_path);
}
- double_up_write_data_sem(orig_inode, donor_inode);
+ ext4_double_up_write_data_sem(orig_inode, donor_inode);
ext4_inode_resume_unlocked_dio(orig_inode);
ext4_inode_resume_unlocked_dio(donor_inode);
- mext_inode_double_unlock(orig_inode, donor_inode);
+ ext4_inode_double_unlock(orig_inode, donor_inode);
return ret;
}