docs: filesystems: convert fuse-io.txt to ReST

- Add a SPDX header;
- Add a document title;
- Add it to filesystems/index.rst.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/88ec8025c1c5fc3ac5b65f1151c41ebcc696dc0e.1588021877.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

1 files changed, 0 insertions, 38 deletions

diff --git a/Documentation/filesystems/fuse-io.txt b/Documentation/filesystems/fuse-io.txt
deleted file mode 100644
index 07b8f73f100f..000000000000
--- a/Documentation/filesystems/fuse-io.txt
+++ /dev/null
@@ -1,38 +0,0 @@
-Fuse supports the following I/O modes:
-
-- direct-io
-- cached
-  + write-through
-  + writeback-cache
-
-The direct-io mode can be selected with the FOPEN_DIRECT_IO flag in the
-FUSE_OPEN reply.
-
-In direct-io mode the page cache is completely bypassed for reads and writes.
-No read-ahead takes place. Shared mmap is disabled.
-
-In cached mode reads may be satisfied from the page cache, and data may be
-read-ahead by the kernel to fill the cache.  The cache is always kept consistent
-after any writes to the file.  All mmap modes are supported.
-
-The cached mode has two sub modes controlling how writes are handled.  The
-write-through mode is the default and is supported on all kernels.  The
-writeback-cache mode may be selected by the FUSE_WRITEBACK_CACHE flag in the
-FUSE_INIT reply.
-
-In write-through mode each write is immediately sent to userspace as one or more
-WRITE requests, as well as updating any cached pages (and caching previously
-uncached, but fully written pages).  No READ requests are ever sent for writes,
-so when an uncached page is partially written, the page is discarded.
-
-In writeback-cache mode (enabled by the FUSE_WRITEBACK_CACHE flag) writes go to
-the cache only, which means that the write(2) syscall can often complete very
-fast.  Dirty pages are written back implicitly (background writeback or page
-reclaim on memory pressure) or explicitly (invoked by close(2), fsync(2) and
-when the last ref to the file is being released on munmap(2)).  This mode
-assumes that all changes to the filesystem go through the FUSE kernel module
-(size and atime/ctime/mtime attributes are kept up-to-date by the kernel), so
-it's generally not suitable for network filesystems.  If a partial page is
-written, then the page needs to be first read from userspace.  This means, that
-even for files opened for O_WRONLY it is possible that READ requests will be
-generated by the kernel.