Documentation: Fix typos

Fix typos in Documentation.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/20230814212822.193684-4-helgaas@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

doc: idmappings: fix an error and rephrase a paragraph

If the modified paragraph is referring to the idmapping mentioned in the
previous paragraph (i.e. `u0:k10000:r10000`), then it is `u0` that the
upper idmapset starts with, not `u1000`.

Fix this error and rephrase this paragraph a bit to make this reference
more explicit.

Reported-by: Wang Lei <wanglei249@huawei.com>
Signed-off-by: GONG, Ruiqi <gongruiqi1@huawei.com>
Message-Id: <20230816033210.914262-1-gongruiqi@huaweicloud.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

docs: filesystems: idmappings: clarify from where idmappings are taken

Let's clarify from where we take idmapping of each type:
- caller
- filesystem
- mount

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Christian Brauner <brauner@kernel.org>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Message-Id: <20230625182047.26854-1-aleksandr.mikhalitsyn@canonical.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Documentation: update idmappings.rst

Quite a lot has changed over the last few kernel releases with the
introduction of vfs{g,u}id_t and struct mnt_idmap. Update the
documentation accordingly.

Cc: Seth Forshee <sforshee@kernel.org>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

Documentation: filesystems: correct possessive "its"

Change occurrences of "it's" that are possessive to "its"
so that they don't read as "it is".

For f2fs.rst, reword one description for better clarity.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-f2fs-devel@lists.sourceforge.net
Cc: linux-xfs@vger.kernel.org
Cc: Christian Brauner <brauner@kernel.org>
Cc: Seth Forshee <sforshee@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: "Christian Brauner (Microsoft)" <brauner@kernel.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>
Link: https://lore.kernel.org/r/20220901002828.25102-1-rdunlap@infradead.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: Add small intro to idmap examples

When reading the documentation, I didn't understand why this list
examples of things that fail without using the mount idmap feature.
It seems pretty pointless and I doubted if I was missing something,
until I finished the examples, the next section and saw the examples
revisited. After that, it all made sense.

Let's add one small sentence before, so the reader knows where this is
going and why examples that don't might seem relevant are used.

Link: https://lore.kernel.org/r/20220429135748.481301-1-rodrigo@sdfg.com.ar
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Rodrigo Campos <rodrigo@sdfg.com.ar>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

docs: update mapping documentation

Now that we implement the full remapping algorithms described in our
documentation remove the section about shortcircuting them.

Link: https://lore.kernel.org/r/20211123114227.3124056-6-brauner@kernel.org (v1)
Link: https://lore.kernel.org/r/20211130121032.3753852-6-brauner@kernel.org (v2)
Link: https://lore.kernel.org/r/20211203111707.3901969-6-brauner@kernel.org
Cc: Seth Forshee <sforshee@digitalocean.com>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
CC: linux-fsdevel@vger.kernel.org
Reviewed-by: Seth Forshee <sforshee@digitalocean.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

doc: give a more thorough id handling explanation

Currently there's no document explaining how idmappings work at all.
Add a document that gives an introduction and also goes into a bit more
detail for more advanced use-cases.

Link: https://lore.kernel.org/r/20210727104416.828293-1-brauner@kernel.org
Cc: Seth Forshee <seth.forshee@digitalocean.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>