diff options
Diffstat (limited to 'Documentation/filesystems/iomap/design.rst')
| -rw-r--r-- | Documentation/filesystems/iomap/design.rst | 25 |
1 files changed, 23 insertions, 2 deletions
diff --git a/Documentation/filesystems/iomap/design.rst b/Documentation/filesystems/iomap/design.rst index b0d0188a095e..f2df9b6df988 100644 --- a/Documentation/filesystems/iomap/design.rst +++ b/Documentation/filesystems/iomap/design.rst @@ -243,8 +243,24 @@ The fields are as follows: regular file data. This is only useful for FIEMAP. - * **IOMAP_F_PRIVATE**: Starting with this value, the upper bits can - be set by the filesystem for its own purposes. + * **IOMAP_F_BOUNDARY**: This indicates I/O and its completion must not be + merged with any other I/O or completion. Filesystems must use this when + submitting I/O to devices that cannot handle I/O crossing certain LBAs + (e.g. ZNS devices). This flag applies only to buffered I/O writeback; all + other functions ignore it. + + * **IOMAP_F_PRIVATE**: This flag is reserved for filesystem private use. + + * **IOMAP_F_ANON_WRITE**: Indicates that (write) I/O does not have a target + block assigned to it yet and the file system will do that in the bio + submission handler, splitting the I/O as needed. + + * **IOMAP_F_ATOMIC_BIO**: This indicates write I/O must be submitted with the + ``REQ_ATOMIC`` flag set in the bio. Filesystems need to set this flag to + inform iomap that the write I/O operation requires torn-write protection + based on HW-offload mechanism. They must also ensure that mapping updates + upon the completion of the I/O must be performed in a single metadata + update. These flags can be set by iomap itself during file operations. The filesystem should supply an ``->iomap_end`` function if it needs @@ -352,6 +368,11 @@ operations: ``IOMAP_NOWAIT`` is often set on behalf of ``IOCB_NOWAIT`` or ``RWF_NOWAIT``. + * ``IOMAP_DONTCACHE`` is set when the caller wishes to perform a + buffered file I/O and would like the kernel to drop the pagecache + after the I/O completes, if it isn't already being used by another + thread. + If it is necessary to read existing file contents from a `different <https://lore.kernel.org/all/20191008071527.29304-9-hch@lst.de/>`_ device or address range on a device, the filesystem should return that |