diff options
| author | Darrick J. Wong <darrick.wong@oracle.com> | 2016-10-03 09:11:14 -0700 |
|---|---|---|
| committer | Darrick J. Wong <darrick.wong@oracle.com> | 2016-10-03 09:11:14 -0700 |
| commit | 71be6b4942dd64bc17728f82f787be98fd8afed7 (patch) | |
| tree | c5a219e8c9d574051b01551d6e24012519213a03 /include/uapi/linux/falloc.h | |
| parent | 0a6eab8bd4e0120d49511acbb294797d96ef9e4a (diff) | |
vfs: add a FALLOC_FL_UNSHARE mode to fallocate to unshare a range of blocks
Add a new fallocate mode flag that explicitly unshares blocks on
filesystems that support such features. The new flag can only
be used with an allocate-mode fallocate call.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Diffstat (limited to 'include/uapi/linux/falloc.h')
| -rw-r--r-- | include/uapi/linux/falloc.h | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/include/uapi/linux/falloc.h b/include/uapi/linux/falloc.h index 3e445a760f14..b075f601919b 100644 --- a/include/uapi/linux/falloc.h +++ b/include/uapi/linux/falloc.h @@ -58,4 +58,22 @@ */ #define FALLOC_FL_INSERT_RANGE 0x20 +/* + * FALLOC_FL_UNSHARE_RANGE is used to unshare shared blocks within the + * file size without overwriting any existing data. The purpose of this + * call is to preemptively reallocate any blocks that are subject to + * copy-on-write. + * + * Different filesystems may implement different limitations on the + * granularity of the operation. Most will limit operations to filesystem + * block size boundaries, but this boundary may be larger or smaller + * depending on the filesystem and/or the configuration of the filesystem + * or file. + * + * This flag can only be used with allocate-mode fallocate, which is + * to say that it cannot be used with the punch, zero, collapse, or + * insert range modes. + */ +#define FALLOC_FL_UNSHARE_RANGE 0x40 + #endif /* _UAPI_FALLOC_H_ */ |