Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
include/linux/pagemap.h | 2 ++
mm/filemap.c | 4 ++++
2 files changed, 6 insertions(+)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 2df35e65557d..e8ac0b32f84d 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -586,6 +586,7 @@ pgoff_t page_cache_prev_miss(struct address_space *mapping,
* * %FGP_CREAT - If no folio is present then a new folio is allocated,
* added to the page cache and the VM's LRU list. The folio is
* returned locked.
+ * * %FGP_CREAT_ONLY - Fail if a folio is not present
* * %FGP_FOR_MMAP - The caller wants to do its own locking dance if the
* folio is already in cache. If the folio was allocated, unlock it
* before returning so the caller can do the same dance.
@@ -606,6 +607,7 @@ typedef unsigned int __bitwise fgf_t;
#define FGP_NOWAIT ((__force fgf_t)0x00000020)
#define FGP_FOR_MMAP ((__force fgf_t)0x00000040)
#define FGP_STABLE ((__force fgf_t)0x00000080)
+#define FGP_CREAT_ONLY ((__force fgf_t)0x00000100)
#define FGF_GET_ORDER(fgf) (((__force unsigned)fgf) >> 26) /* top 6 bits */
#define FGP_WRITEBEGIN (FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE)
diff --git a/mm/filemap.c b/mm/filemap.c
index 750e779c23db..d5107bd0cd09 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1854,6 +1854,10 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
folio = NULL;
if (!folio)
goto no_page;
+ if (fgp_flags & FGP_CREAT_ONLY) {
+ folio_put(folio);
+ return ERR_PTR(-EEXIST);
+ }
if (fgp_flags & FGP_LOCK) {
if (fgp_flags & FGP_NOWAIT) {
--
2.39.0
