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Diffstat (limited to 'Documentation/filesystems/iomap/design.rst')
| -rw-r--r-- | Documentation/filesystems/iomap/design.rst | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/Documentation/filesystems/iomap/design.rst b/Documentation/filesystems/iomap/design.rst index e29651a42eec..0f7672676c0b 100644 --- a/Documentation/filesystems/iomap/design.rst +++ b/Documentation/filesystems/iomap/design.rst @@ -167,7 +167,6 @@ structure below: struct dax_device *dax_dev; void *inline_data; void *private; - const struct iomap_folio_ops *folio_ops; u64 validity_cookie; }; @@ -243,13 +242,25 @@ 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 to observe these flags: @@ -280,8 +291,6 @@ The fields are as follows: <https://lore.kernel.org/all/20180619164137.13720-7-hch@lst.de/>`_. This value will be passed unchanged to ``->iomap_end``. - * ``folio_ops`` will be covered in the section on pagecache operations. - * ``validity_cookie`` is a magic freshness value set by the filesystem that should be used to detect stale mappings. For pagecache operations this is critical for correct operation |