Merge tag 'vfs-6.10-rc2.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs fixes from Christian Brauner:

 - Fix io_uring based write-through after converting cifs to use the
   netfs library

 - Fix aio error handling when doing write-through via netfs library

 - Fix performance regression in iomap when used with non-large folio
   mappings

 - Fix signalfd error code

 - Remove obsolete comment in signalfd code

 - Fix async request indication in netfs_perform_write() by raising
   BDP_ASYNC when IOCB_NOWAIT is set

 - Yield swap device immediately to prevent spurious EBUSY errors

 - Don't cross a .backup mountpoint from backup volumes in afs to avoid
   infinite loops

 - Fix a race between umount and async request completion in 9p after 9p
   was converted to use the netfs library

* tag 'vfs-6.10-rc2.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  netfs, 9p: Fix race between umount and async request completion
  afs: Don't cross .backup mountpoint from backup volume
  swap: yield device immediately
  netfs: Fix setting of BDP_ASYNC from iocb flags
  signalfd: drop an obsolete comment
  signalfd: fix error return code
  iomap: fault in smaller chunks for non-large folio mappings
  filemap: add helper mapping_max_folio_size()
  netfs: Fix AIO error handling when doing write-through
  netfs: Fix io_uring based write-through

2 files changed, 39 insertions, 13 deletions

diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index d2d291a9cdad..3ca3906bb8da 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -68,6 +68,7 @@ struct netfs_inode {
 	loff_t			remote_i_size;	/* Size of the remote file */
 	loff_t			zero_point;	/* Size after which we assume there's no data
 						 * on the server */
+	atomic_t		io_count;	/* Number of outstanding reqs */
 	unsigned long		flags;
 #define NETFS_ICTX_ODIRECT	0		/* The file has DIO in progress */
 #define NETFS_ICTX_UNBUFFERED	1		/* I/O should not use the pagecache */
@@ -474,6 +475,7 @@ static inline void netfs_inode_init(struct netfs_inode *ctx,
 	ctx->remote_i_size = i_size_read(&ctx->inode);
 	ctx->zero_point = LLONG_MAX;
 	ctx->flags = 0;
+	atomic_set(&ctx->io_count, 0);
 #if IS_ENABLED(CONFIG_FSCACHE)
 	ctx->cache = NULL;
 #endif
@@ -517,4 +519,20 @@ static inline struct fscache_cookie *netfs_i_cookie(struct netfs_inode *ctx)
 #endif
 }
 
+/**
+ * netfs_wait_for_outstanding_io - Wait for outstanding I/O to complete
+ * @ctx: The netfs inode to wait on
+ *
+ * Wait for outstanding I/O requests of any type to complete.  This is intended
+ * to be called from inode eviction routines.  This makes sure that any
+ * resources held by those requests are cleaned up before we let the inode get
+ * cleaned up.
+ */
+static inline void netfs_wait_for_outstanding_io(struct inode *inode)
+{
+	struct netfs_inode *ictx = netfs_inode(inode);
+
+	wait_var_event(&ictx->io_count, atomic_read(&ictx->io_count) == 0);
+}
+
 #endif /* _LINUX_NETFS_H */
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 3d69589c00a4..ee633712bba0 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -346,6 +346,19 @@ static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
 	m->gfp_mask = mask;
 }
 
+/*
+ * There are some parts of the kernel which assume that PMD entries
+ * are exactly HPAGE_PMD_ORDER.  Those should be fixed, but until then,
+ * limit the maximum allocation order to PMD size.  I'm not aware of any
+ * assumptions about maximum order if THP are disabled, but 8 seems like
+ * a good order (that's 1MB if you're using 4kB pages)
+ */
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#define MAX_PAGECACHE_ORDER	HPAGE_PMD_ORDER
+#else
+#define MAX_PAGECACHE_ORDER	8
+#endif
+
 /**
  * mapping_set_large_folios() - Indicate the file supports large folios.
  * @mapping: The file.
@@ -372,6 +385,14 @@ static inline bool mapping_large_folio_support(struct address_space *mapping)
 		test_bit(AS_LARGE_FOLIO_SUPPORT, &mapping->flags);
 }
 
+/* Return the maximum folio size for this pagecache mapping, in bytes. */
+static inline size_t mapping_max_folio_size(struct address_space *mapping)
+{
+	if (mapping_large_folio_support(mapping))
+		return PAGE_SIZE << MAX_PAGECACHE_ORDER;
+	return PAGE_SIZE;
+}
+
 static inline int filemap_nr_thps(struct address_space *mapping)
 {
 #ifdef CONFIG_READ_ONLY_THP_FOR_FS
@@ -530,19 +551,6 @@ static inline void *detach_page_private(struct page *page)
 	return folio_detach_private(page_folio(page));
 }
 
-/*
- * There are some parts of the kernel which assume that PMD entries
- * are exactly HPAGE_PMD_ORDER.  Those should be fixed, but until then,
- * limit the maximum allocation order to PMD size.  I'm not aware of any
- * assumptions about maximum order if THP are disabled, but 8 seems like
- * a good order (that's 1MB if you're using 4kB pages)
- */
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-#define MAX_PAGECACHE_ORDER	HPAGE_PMD_ORDER
-#else
-#define MAX_PAGECACHE_ORDER	8
-#endif
-
 #ifdef CONFIG_NUMA
 struct folio *filemap_alloc_folio_noprof(gfp_t gfp, unsigned int order);
 #else