From: Josef Bacik <josef@xxxxxxxxxxxxxx> We queue up inodes to be defrag'ed asynchronously, which means we do not have their original file for readahead. This means that the code to skip readahead on pre-content watched files will not run, and we could potentially read in empty pages. Handle this corner case by disabling defrag on files that are currently being watched for pre-content events. Signed-off-by: Josef Bacik <josef@xxxxxxxxxxxxxx> Signed-off-by: Jan Kara <jack@xxxxxxx> Link: https://patch.msgid.link/4cc5bcea13db7904174353d08e85157356282a59.1731684329.git.josef@xxxxxxxxxxxxxx --- fs/btrfs/ioctl.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 226c91fe31a7..a908f75458f0 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -2638,6 +2638,15 @@ static int btrfs_ioctl_defrag(struct file *file, void __user *argp) goto out; } + /* + * Don't allow defrag on pre-content watched files, as it could + * populate the page cache with 0's via readahead. + */ + if (unlikely(FMODE_FSNOTIFY_HSM(file->f_mode))) { + ret = -EINVAL; + goto out; + } + if (argp) { if (copy_from_user(&range, argp, sizeof(range))) { ret = -EFAULT; -- 2.35.3
