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docs: fs: convert docs without extension to ReST

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There are 3 remaining files without an extension inside the fs docs
dir.

Manually convert them to ReST.

In the case of the nfs/exporting.rst file, as the nfs docs
aren't ported yet, I opted to convert and add a :orphan: there,
with should be removed when it gets added into a nfs-specific
part of the fs documentation.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This commit is contained in:
Mauro Carvalho Chehab 2019-07-26 09:51:27 -03:00 • committed by Jonathan Corbet
parent 5a5e045bb3
commit ec23eb54fb
11 changed files with 225 additions and 119 deletions
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31
Documentation/filesystems/nfs/Exporting → Documentation/filesystems/nfs/exporting.rst
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@ -1,3 +1,4 @@
:orphan:
Making Filesystems Exportable
=============================
@ -42,9 +43,9 @@ filehandle fragment, there is no automatic creation of a path prefix
for the object. This leads to two related but distinct features of
the dcache that are not needed for normal filesystem access.
1/ The dcache must sometimes contain objects that are not part of the
1. The dcache must sometimes contain objects that are not part of the
proper prefix. i.e that are not connected to the root.
2/ The dcache must be prepared for a newly found (via ->lookup) directory
2. The dcache must be prepared for a newly found (via ->lookup) directory
to already have a (non-connected) dentry, and must be able to move
that dentry into place (based on the parent and name in the
->lookup). This is particularly needed for directories as
@ -52,7 +53,7 @@ the dcache that are not needed for normal filesystem access.
To implement these features, the dcache has:
a/ A dentry flag DCACHE_DISCONNECTED which is set on
a. A dentry flag DCACHE_DISCONNECTED which is set on
any dentry that might not be part of the proper prefix.
This is set when anonymous dentries are created, and cleared when a
dentry is noticed to be a child of a dentry which is in the proper
@ -71,48 +72,52 @@ a/ A dentry flag DCACHE_DISCONNECTED which is set on
dentries. That guarantees that we won't need to hunt them down upon
umount.
b/ A primitive for creation of secondary roots - d_obtain_root(inode).
b. A primitive for creation of secondary roots - d_obtain_root(inode).
Those do _not_ bear DCACHE_DISCONNECTED. They are placed on the
per-superblock list (->s_roots), so they can be located at umount
time for eviction purposes.
c/ Helper routines to allocate anonymous dentries, and to help attach
c. Helper routines to allocate anonymous dentries, and to help attach
loose directory dentries at lookup time. They are:
d_obtain_alias(inode) will return a dentry for the given inode.
If the inode already has a dentry, one of those is returned.
If it doesn't, a new anonymous (IS_ROOT and
DCACHE_DISCONNECTED) dentry is allocated and attached.
DCACHE_DISCONNECTED) dentry is allocated and attached.
In the case of a directory, care is taken that only one dentry
can ever be attached.
d_splice_alias(inode, dentry) will introduce a new dentry into the tree;
either the passed-in dentry or a preexisting alias for the given inode
(such as an anonymous one created by d_obtain_alias), if appropriate.
It returns NULL when the passed-in dentry is used, following the calling
convention of ->lookup.
Filesystem Issues
-----------------
For a filesystem to be exportable it must:
1/ provide the filehandle fragment routines described below.
2/ make sure that d_splice_alias is used rather than d_add
1. provide the filehandle fragment routines described below.
2. make sure that d_splice_alias is used rather than d_add
when ->lookup finds an inode for a given parent and name.
If inode is NULL, d_splice_alias(inode, dentry) is equivalent to
If inode is NULL, d_splice_alias(inode, dentry) is equivalent to::
d_add(dentry, inode), NULL
Similarly, d_splice_alias(ERR_PTR(err), dentry) = ERR_PTR(err)
Typically the ->lookup routine will simply end with a:
Typically the ->lookup routine will simply end with a::
return d_splice_alias(inode, dentry);
}
A file system implementation declares that instances of the filesystem
A file system implementation declares that instances of the filesystem
are exportable by setting the s_export_op field in the struct
super_block. This field must point to a "struct export_operations"
struct which has the following members: