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-rw-r--r--Documentation/filesystems/vfs.txt5
1 files changed, 5 insertions, 0 deletions
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index 7737bfd03cf..ea271f2d395 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -617,6 +617,11 @@ struct address_space_operations {
In this case the prepare_write will be retried one the lock is
regained.
+ Note: the page _must not_ be marked uptodate in this function
+ (or anywhere else) unless it actually is uptodate right now. As
+ soon as a page is marked uptodate, it is possible for a concurrent
+ read(2) to copy it to userspace.
+
commit_write: If prepare_write succeeds, new data will be copied
into the page and then commit_write will be called. It will
typically update the size of the file (if appropriate) and