Now we have introduced the ability to specify that actions should be taken after a VMA is established via the vm_area_desc->action field as specified in mmap_prepare, update both the VFS documentation and the porting guide to describe this. Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx> --- Documentation/filesystems/porting.rst | 5 +++++ Documentation/filesystems/vfs.rst | 4 ++++ 2 files changed, 9 insertions(+) diff --git a/Documentation/filesystems/porting.rst b/Documentation/filesystems/porting.rst index 85f590254f07..6743ed0b9112 100644 --- a/Documentation/filesystems/porting.rst +++ b/Documentation/filesystems/porting.rst @@ -1285,3 +1285,8 @@ rather than a VMA, as the VMA at this stage is not yet valid. The vm_area_desc provides the minimum required information for a filesystem to initialise state upon memory mapping of a file-backed region, and output parameters for the file system to set this state. + +In nearly all cases, this is all that is required for a filesystem. However, if +a filesystem needs to perform an operation such a pre-population of page tables, +then that action can be specified in the vm_area_desc->action field, which can +be configured using the mmap_action_*() helpers. diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst index 486a91633474..9e96c46ee10e 100644 --- a/Documentation/filesystems/vfs.rst +++ b/Documentation/filesystems/vfs.rst @@ -1236,6 +1236,10 @@ otherwise noted. file-backed memory mapping, most notably establishing relevant private state and VMA callbacks. + If further action such as pre-population of page tables is required, + this can be specified by the vm_area_desc->action field and related + parameters. + Note that the file operations are implemented by the specific filesystem in which the inode resides. When opening a device node (character or block special) most filesystems will call special -- 2.51.0
