ext4: elevate write count for migrate ioctl

Aneesh Kumar K.V
2008-09-12T09:04:24Z

From: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

This patch hooks the ext3 to ext4 migrate interface to
EXT4_IOC_SETFLAGS ioctl. The userspace interface is via
chattr +e. We only allow setting extent flags. Clearing
extent flag (migrating from ext4 to ext3) is not supported.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
fs/ext4/ext4.h | 2 +-
fs/ext4/ioctl.c | 17 ++++++++++++++++-
2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 103892b..70e8486 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -250,7 +250,7 @@ struct flex_groups {
#define EXT4_RESERVED_FL 0x80000000 /* reserved for ext4 lib */

#define EXT4_FL_USER_VISIBLE 0x000BDFFF /* User visible flags */
-#define EXT4_FL_USER_MODIFIABLE 0x000380FF /* User modifiable flags */
+#define EXT4_FL_USER_MODIFIABLE 0x000B80FF /* User modifiable flags */

/*
* Inode dynamic state flags
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 6e02967..94cdd02 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -34,7 +34,7 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
return put_user(flags, (int __user *) arg);
case EXT4_IOC_SETFLAGS: {
handle_t *handle = NULL;
- int err;
+ int err, migrate = 0;
struct ext4_iloc iloc;
unsigned int oldflags;
unsigned int jflag;
@@ -82,6 +82,17 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
if (!capable(CAP_SYS_RESOURCE))
goto flags_out;
}
+ if (oldflags & EXT4_EXTENTS_FL) {
+ /* We don't support clearning extent flags */
+ if (!(flags & EXT4_EXTENTS_FL)) {
+ err = -EOPNOTSUPP;
+ goto flags_out;
+ }
+ } else if (flags & EXT4_EXTENTS_FL) {
+ /* migrate the file */
+ migrate = 1;
+ flags &= ~EXT4_EXTENTS_FL;
+ }

handle = ext4_journal_start(inode, 1);
if (IS_ERR(handle)) {
@@ -109,6 +120,10 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)

if ((jflag ^ oldflags) & (EXT4_JOURNAL_DATA_FL))
err = ext4_change_inode_journal_flag(inode, jflag);
+ if (err)
+ goto flags_out;
+ if (migrate)
+ err = ext4_ext_migrate(inode);
flags_out:
mutex_unlock(&inode->i_mutex);
mnt_drop_write(filp->f_path.mnt);