After introducing pre-content events, we had a regression related to
disabling huge faults on files that should never have pre-content events
enabled.
This happened because the default f_mode of allocated files (0) does
not disable pre-content events.
Pre-content events are disabled in file_set_fsnotify_mode_by_watchers()
but internal files may not get to call this helper.
Initialize f_mode to disable permission and pre-content events for all
files and if needed they will be enabled for the callers of
file_set_fsnotify_mode_by_watchers().
Fixes: 20bf82a898b6 ("mm: don't allow huge faults for files with pre content watches")
Reported-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
Closes: https://lore.kernel.org/linux-fsdevel/20250131121703.1e4d00a7.alex.williamson@xxxxxxxxxx/
Tested-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/file_table.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/fs/file_table.c b/fs/file_table.c
index 35b93da6c5cb1..5c00dc38558da 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -194,6 +194,11 @@ static int init_file(struct file *f, int flags, const struct cred *cred)
* refcount bumps we should reinitialize the reused file first.
*/
file_ref_init(&f->f_ref, 1);
+ /*
+ * Disable permission and pre-content events for all files by default.
+ * They may be enabled later by file_set_fsnotify_mode_from_watchers().
+ */
+ file_set_fsnotify_mode(f, FMODE_NONOTIFY_PERM);
return 0;
}
--
2.34.1
