diff mbox series

[v7,17/18] btrfs: disable defrag on pre-content watched files

Message ID 6d9ff819edb6df5583844c26169dc6ddd471316d.1731433903.git.josef@toxicpanda.com (mailing list archive)
State New
Headers show
Series fanotify: add pre-content hooks | expand

Commit Message

Josef Bacik Nov. 12, 2024, 5:55 p.m. UTC 
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@toxicpanda.com>
---
 fs/btrfs/ioctl.c | 9 +++++++++
 1 file changed, 9 insertions(+)
diff mbox series

Patch

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index c9302d193187..1e5913f276be 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2635,6 +2635,15 @@  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 (fsnotify_file_has_pre_content_watches(file)) {
+			ret = -EINVAL;
+			goto out;
+		}
+
 		if (argp) {
 			if (copy_from_user(&range, argp, sizeof(range))) {
 				ret = -EFAULT;