[PATCH v2 14/16] bcachefs: add pre-content fsnotify hook to fault

Josef Bacik
2024-08-08T19:28:35Z

bcachefs has its own locking around filemap_fault, so we have to make
sure we do the fsnotify hook before the locking. Add the check to emit
the event before the locking and return VM_FAULT_RETRY to retrigger the
fault once the event has been emitted.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
fs/bcachefs/fs-io-pagecache.c | 13 +++++++++++++
1 file changed, 13 insertions(+)

diff --git a/fs/bcachefs/fs-io-pagecache.c b/fs/bcachefs/fs-io-pagecache.c
index a9cc5cad9cc9..359856df52d4 100644
--- a/fs/bcachefs/fs-io-pagecache.c
+++ b/fs/bcachefs/fs-io-pagecache.c
@@ -562,6 +562,7 @@ void bch2_set_folio_dirty(struct bch_fs *c,
vm_fault_t bch2_page_fault(struct vm_fault *vmf)
{
struct file *file = vmf->vma->vm_file;
+ struct file *fpin = NULL;
struct address_space *mapping = file->f_mapping;
struct address_space *fdm = faults_disabled_mapping();
struct bch_inode_info *inode = file_bch_inode(file);
@@ -570,6 +571,18 @@ vm_fault_t bch2_page_fault(struct vm_fault *vmf)
if (fdm == mapping)
return VM_FAULT_SIGBUS;

+ ret = filemap_maybe_emit_fsnotify_event(vmf, &fpin);
+ if (unlikely(ret)) {
+ if (fpin) {
+ fput(fpin);
+ ret |= VM_FAULT_RETRy;
+ }
+ return ret;
+ } else if (fpin) {
+ fput(fpin);
+ return VM_FAULT_RETRY;
+ }
+
/* Lock ordering: */
if (fdm > mapping) {
struct bch_inode_info *fdm_host = to_bch_ei(fdm->host);
--
2.43.0