Redfs ubuntu noble 6.8.0 58.60 updates

fs/fuse/dir.c

@@ -2074,15 +2074,32 @@ int fuse_do_setattr(struct dentry *dentry, struct iattr *attr,
 		WARN_ON(!(attr->ia_valid & ATTR_SIZE));
 		WARN_ON(attr->ia_size != 0);
 		if (fc->atomic_o_trunc) {
+			struct percpu_rw_semaphore *wb_sem = fi->wb_inval_rwsem;
+
 			/*
 			 * No need to send request to userspace, since actual
 			 * truncation has already been done by OPEN.  But still
 			 * need to truncate page cache.
+			 *
+			 * Revoke and drop under the coherency gate write side,
+			 * like the NOTIFY invalidate path: a gate reader that
+			 * already re-validated its grant must not have the
+			 * lock tree and the cache yanked mid-hold, or it
+			 * would repopulate the truncated range trusting a
+			 * grant that no longer exists.  Waiting for gate
+			 * readers here is safe: we hold i_rwsem exclusive, so
+			 * no gate holder can be waiting on it (the write path
+			 * takes i_rwsem before the gate, the read path never
+			 * takes it).
 			 */
+			if (wb_sem)
+				percpu_down_write(wb_sem);
 			if (fc->dlm && fc->writeback_cache)
 				fuse_dlm_cache_release_locks(fi);
 			i_size_write(inode, 0);
 			truncate_pagecache(inode, 0);
+			if (wb_sem)
+				percpu_up_write(wb_sem);
 			goto out;
 		}
 		file = NULL;
@@ -2186,11 +2203,23 @@ int fuse_do_setattr(struct dentry *dentry, struct iattr *attr,
 	 */
 	if ((is_truncate || !is_wb) &&
 	    S_ISREG(inode->i_mode) && oldsize != outarg.attr.size) {
+		struct percpu_rw_semaphore *wb_sem = fi->wb_inval_rwsem;
+
+		/*
+		 * Revoke and drop under the coherency gate write side; see
+		 * the atomic-O_TRUNC branch above.  i_rwsem is held
+		 * exclusive here as well (setattr), so waiting out gate
+		 * readers cannot deadlock.
+		 */
+		if (wb_sem)
+			percpu_down_write(wb_sem);
 		if (fc->dlm && fc->writeback_cache)
 			fuse_dlm_unlock_range(fi, outarg.attr.size & PAGE_MASK, -1);
 
 		truncate_pagecache(inode, outarg.attr.size);
 		invalidate_inode_pages2(mapping);
+		if (wb_sem)
+			percpu_up_write(wb_sem);
 	}
 
 	clear_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);