[PATCH 10/11] iomap: add a IOMAP_DIO_OVERWRITE_ONLY flag
From: Christoph Hellwig <hch@lst.de>
Date: 2021-01-21 09:12:46
Also in:
linux-fsdevel
Subsystem:
filesystems (vfs and infrastructure), filesystems [iomap], the rest · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds
Add a flag to signal an only pure overwrites are allowed. Signed-off-by: Christoph Hellwig <hch@lst.de> --- fs/iomap/direct-io.c | 7 +++++++ include/linux/iomap.h | 8 ++++++++ 2 files changed, 15 insertions(+)
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 947343730e2c93..65d32364345d22 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c@@ -485,6 +485,13 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, iomap_flags |= IOMAP_NOWAIT; } + if (dio_flags & IOMAP_DIO_OVERWRITE_ONLY) { + ret = -EAGAIN; + if (pos >= dio->i_size || pos + count > dio->i_size) + goto out_free_dio; + iomap_flags |= IOMAP_OVERWRITE_ONLY; + } + ret = filemap_write_and_wait_range(mapping, pos, end); if (ret) goto out_free_dio;
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index be4e1e1e01e801..cfa20afd7d5b87 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h@@ -122,6 +122,7 @@ struct iomap_page_ops { #define IOMAP_FAULT (1 << 3) /* mapping for page fault */ #define IOMAP_DIRECT (1 << 4) /* direct I/O */ #define IOMAP_NOWAIT (1 << 5) /* do not block */ +#define IOMAP_OVERWRITE_ONLY (1 << 6) /* purely overwrites allowed */ struct iomap_ops { /*
@@ -262,6 +263,13 @@ struct iomap_dio_ops { */ #define IOMAP_DIO_FORCE_WAIT (1 << 0) +/* + * Do not allocate blocks or zero partial blocks, but instead fall back to + * the caller by returning -EAGAIN. Used to optimize direct I/O writes that + * are not aligned to the file system block size. + */ +#define IOMAP_DIO_OVERWRITE_ONLY (1 << 1) + ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, const struct iomap_ops *ops, const struct iomap_dio_ops *dops, unsigned int dio_flags);
--
2.29.2