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author | Matthew Bobrowski <mbobrowski@mbobrowski.org> | 2019-11-05 15:02:39 +0300 |
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committer | Theodore Ts'o <tytso@mit.edu> | 2019-11-05 23:53:28 +0300 |
commit | 378f32bab3714f04c4e0c3aee4129f6703805550 (patch) | |
tree | b92c0befad4b30456d68d7847811f38f7e2ff507 /fs/iomap/Makefile | |
parent | 3eaf9cc62f447a742b26fa601993e94406aa1ea1 (diff) | |
download | linux-378f32bab3714f04c4e0c3aee4129f6703805550.tar.xz |
ext4: introduce direct I/O write using iomap infrastructure
This patch introduces a new direct I/O write path which makes use of
the iomap infrastructure.
All direct I/O writes are now passed from the ->write_iter() callback
through to the new direct I/O handler ext4_dio_write_iter(). This
function is responsible for calling into the iomap infrastructure via
iomap_dio_rw().
Code snippets from the existing direct I/O write code within
ext4_file_write_iter() such as, checking whether the I/O request is
unaligned asynchronous I/O, or whether the write will result in an
overwrite have effectively been moved out and into the new direct I/O
->write_iter() handler.
The block mapping flags that are eventually passed down to
ext4_map_blocks() from the *_get_block_*() suite of routines have been
taken out and introduced within ext4_iomap_alloc().
For inode extension cases, ext4_handle_inode_extension() is
effectively the function responsible for performing such metadata
updates. This is called after iomap_dio_rw() has returned so that we
can safely determine whether we need to potentially truncate any
allocated blocks that may have been prepared for this direct I/O
write. We don't perform the inode extension, or truncate operations
from the ->end_io() handler as we don't have the original I/O 'length'
available there. The ->end_io() however is responsible fo converting
allocated unwritten extents to written extents.
In the instance of a short write, we fallback and complete the
remainder of the I/O using buffered I/O via
ext4_buffered_write_iter().
The existing buffer_head direct I/O implementation has been removed as
it's now redundant.
[ Fix up ext4_dio_write_iter() per Jan's comments at
https://lore.kernel.org/r/20191105135932.GN22379@quack2.suse.cz -- TYT ]
Signed-off-by: Matthew Bobrowski <mbobrowski@mbobrowski.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/e55db6f12ae6ff017f36774135e79f3e7b0333da.1572949325.git.mbobrowski@mbobrowski.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/iomap/Makefile')
0 files changed, 0 insertions, 0 deletions