diff options
Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/iomap/operations.rst | 32 |
1 files changed, 14 insertions, 18 deletions
diff --git a/Documentation/filesystems/iomap/operations.rst b/Documentation/filesystems/iomap/operations.rst index 3b628e370d88..f07c8fdb2046 100644 --- a/Documentation/filesystems/iomap/operations.rst +++ b/Documentation/filesystems/iomap/operations.rst @@ -271,7 +271,7 @@ writeback. It does not lock ``i_rwsem`` or ``invalidate_lock``. The dirty bit will be cleared for all folios run through the -``->map_blocks`` machinery described below even if the writeback fails. +``->writeback_range`` machinery described below even if the writeback fails. This is to prevent dirty folio clots when storage devices fail; an ``-EIO`` is recorded for userspace to collect via ``fsync``. @@ -283,15 +283,14 @@ The ``ops`` structure must be specified and is as follows: .. code-block:: c struct iomap_writeback_ops { - int (*map_blocks)(struct iomap_writepage_ctx *wpc, struct inode *inode, - loff_t offset, unsigned len); - int (*submit_ioend)(struct iomap_writepage_ctx *wpc, int status); - void (*discard_folio)(struct folio *folio, loff_t pos); + int (*writeback_range)(struct iomap_writepage_ctx *wpc, + struct folio *folio, u64 pos, unsigned int len, u64 end_pos); + int (*submit_ioend)(struct iomap_writepage_ctx *wpc, int status); }; The fields are as follows: - - ``map_blocks``: Sets ``wpc->iomap`` to the space mapping of the file + - ``writeback_range``: Sets ``wpc->iomap`` to the space mapping of the file range (in bytes) given by ``offset`` and ``len``. iomap calls this function for each dirty fs block in each dirty folio, though it will `reuse mappings @@ -306,6 +305,15 @@ The fields are as follows: This revalidation must be open-coded by the filesystem; it is unclear if ``iomap::validity_cookie`` can be reused for this purpose. + + If this methods fails to schedule I/O for any part of a dirty folio, it + should throw away any reservations that may have been made for the write. + The folio will be marked clean and an ``-EIO`` recorded in the + pagecache. + Filesystems can use this callback to `remove + <https://lore.kernel.org/all/20201029163313.1766967-1-bfoster@redhat.com/>`_ + delalloc reservations to avoid having delalloc reservations for + clean pagecache. This function must be supplied by the filesystem. - ``submit_ioend``: Allows the file systems to hook into writeback bio @@ -316,18 +324,6 @@ The fields are as follows: transactions from process context before submitting the bio. This function is optional. - - ``discard_folio``: iomap calls this function after ``->map_blocks`` - fails to schedule I/O for any part of a dirty folio. - The function should throw away any reservations that may have been - made for the write. - The folio will be marked clean and an ``-EIO`` recorded in the - pagecache. - Filesystems can use this callback to `remove - <https://lore.kernel.org/all/20201029163313.1766967-1-bfoster@redhat.com/>`_ - delalloc reservations to avoid having delalloc reservations for - clean pagecache. - This function is optional. - Pagecache Writeback Completion ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |