Requiring a rw descriptor conflicts both ways with exec, returning ETXTBSY
whenever you try to defrag a program that's currently being run, or
causing intermittent exec failures on a live system being defragged.
As defrag doesn't change the file's contents in any way, there's no reason
to consider it a rw operation. Thus, let's check only whether the file
could have been opened rw. Such access control is still needed as
currently defrag can use extra disk space, and might trigger bugs.
Signed-off-by: Adam Borowski <kilobyte@xxxxxxxxxx>
---
fs/btrfs/ioctl.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 632e26d6f7ce..b75db9d72106 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2561,7 +2561,8 @@ static int btrfs_ioctl_defrag(struct file *file, void __user *argp)
ret = btrfs_defrag_root(root);
break;
case S_IFREG:
- if (!(file->f_mode & FMODE_WRITE)) {
+ if (!capable(CAP_SYS_ADMIN) &&
+ inode_permission(inode, MAY_WRITE)) {
ret = -EINVAL;
goto out;
}
--
2.17.0
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