From: Mauro Carvalho Chehab Date: Mon, 27 Apr 2020 21:17:06 +0000 (+0200) Subject: docs: filesystems: convert fuse-io.txt to ReST X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=ba302d2a8ef0917a6d1c3775d1b4b9f2b26c8ef5;p=linux.git 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 Link: https://lore.kernel.org/r/88ec8025c1c5fc3ac5b65f1151c41ebcc696dc0e.1588021877.git.mchehab+huawei@kernel.org Signed-off-by: Jonathan Corbet --- diff --git a/Documentation/filesystems/fuse-io.rst b/Documentation/filesystems/fuse-io.rst new file mode 100644 index 0000000000000..255a368fe534b --- /dev/null +++ b/Documentation/filesystems/fuse-io.rst @@ -0,0 +1,44 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============== +Fuse I/O Modes +============== + +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. diff --git a/Documentation/filesystems/fuse-io.txt b/Documentation/filesystems/fuse-io.txt deleted file mode 100644 index 07b8f73f100f6..0000000000000 --- 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. diff --git a/Documentation/filesystems/index.rst b/Documentation/filesystems/index.rst index 597ea3ed415ba..ace804c4c3ab6 100644 --- a/Documentation/filesystems/index.rst +++ b/Documentation/filesystems/index.rst @@ -83,6 +83,7 @@ Documentation for filesystem implementations. hfsplus hpfs fuse + fuse-io inotify isofs nilfs2