diff options
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/filesystems/nfs/Exporting | 38 | ||||
-rw-r--r-- | Documentation/filesystems/vfs.txt | 3 |
2 files changed, 25 insertions, 16 deletions
diff --git a/Documentation/filesystems/nfs/Exporting b/Documentation/filesystems/nfs/Exporting index e543b1a619cc..c8f036a9b13f 100644 --- a/Documentation/filesystems/nfs/Exporting +++ b/Documentation/filesystems/nfs/Exporting | |||
@@ -66,23 +66,31 @@ b/ A per-superblock list "s_anon" of dentries which are the roots of | |||
66 | 66 | ||
67 | c/ Helper routines to allocate anonymous dentries, and to help attach | 67 | c/ Helper routines to allocate anonymous dentries, and to help attach |
68 | loose directory dentries at lookup time. They are: | 68 | loose directory dentries at lookup time. They are: |
69 | d_alloc_anon(inode) will return a dentry for the given inode. | 69 | d_obtain_alias(inode) will return a dentry for the given inode. |
70 | If the inode already has a dentry, one of those is returned. | 70 | If the inode already has a dentry, one of those is returned. |
71 | If it doesn't, a new anonymous (IS_ROOT and | 71 | If it doesn't, a new anonymous (IS_ROOT and |
72 | DCACHE_DISCONNECTED) dentry is allocated and attached. | 72 | DCACHE_DISCONNECTED) dentry is allocated and attached. |
73 | In the case of a directory, care is taken that only one dentry | 73 | In the case of a directory, care is taken that only one dentry |
74 | can ever be attached. | 74 | can ever be attached. |
75 | d_splice_alias(inode, dentry) will make sure that there is a | 75 | d_splice_alias(inode, dentry) or d_materialise_unique(dentry, inode) |
76 | dentry with the same name and parent as the given dentry, and | 76 | will introduce a new dentry into the tree; either the passed-in |
77 | which refers to the given inode. | 77 | dentry or a preexisting alias for the given inode (such as an |
78 | If the inode is a directory and already has a dentry, then that | 78 | anonymous one created by d_obtain_alias), if appropriate. The two |
79 | dentry is d_moved over the given dentry. | 79 | functions differ in their handling of directories with preexisting |
80 | If the passed dentry gets attached, care is taken that this is | 80 | aliases: |
81 | mutually exclusive to a d_alloc_anon operation. | 81 | d_splice_alias will use any existing IS_ROOT dentry, but it will |
82 | If the passed dentry is used, NULL is returned, else the used | 82 | return -EIO rather than try to move a dentry with a different |
83 | dentry is returned. This corresponds to the calling pattern of | 83 | parent. This is appropriate for local filesystems, which |
84 | ->lookup. | 84 | should never see such an alias unless the filesystem is |
85 | 85 | corrupted somehow (for example, if two on-disk directory | |
86 | entries refer to the same directory.) | ||
87 | d_materialise_unique will attempt to move any dentry. This is | ||
88 | appropriate for distributed filesystems, where finding a | ||
89 | directory other than where we last cached it may be a normal | ||
90 | consequence of concurrent operations on other hosts. | ||
91 | Both functions return NULL when the passed-in dentry is used, | ||
92 | following the calling convention of ->lookup. | ||
93 | |||
86 | 94 | ||
87 | Filesystem Issues | 95 | Filesystem Issues |
88 | ----------------- | 96 | ----------------- |
@@ -120,12 +128,12 @@ struct which has the following members: | |||
120 | 128 | ||
121 | fh_to_dentry (mandatory) | 129 | fh_to_dentry (mandatory) |
122 | Given a filehandle fragment, this should find the implied object and | 130 | Given a filehandle fragment, this should find the implied object and |
123 | create a dentry for it (possibly with d_alloc_anon). | 131 | create a dentry for it (possibly with d_obtain_alias). |
124 | 132 | ||
125 | fh_to_parent (optional but strongly recommended) | 133 | fh_to_parent (optional but strongly recommended) |
126 | Given a filehandle fragment, this should find the parent of the | 134 | Given a filehandle fragment, this should find the parent of the |
127 | implied object and create a dentry for it (possibly with d_alloc_anon). | 135 | implied object and create a dentry for it (possibly with |
128 | May fail if the filehandle fragment is too small. | 136 | d_obtain_alias). May fail if the filehandle fragment is too small. |
129 | 137 | ||
130 | get_parent (optional but strongly recommended) | 138 | get_parent (optional but strongly recommended) |
131 | When given a dentry for a directory, this should return a dentry for | 139 | When given a dentry for a directory, this should return a dentry for |
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index a1d0d7a30165..61d65cc65c54 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt | |||
@@ -1053,7 +1053,8 @@ struct dentry_operations { | |||
1053 | If the 'rcu_walk' parameter is true, then the caller is doing a | 1053 | If the 'rcu_walk' parameter is true, then the caller is doing a |
1054 | pathwalk in RCU-walk mode. Sleeping is not permitted in this mode, | 1054 | pathwalk in RCU-walk mode. Sleeping is not permitted in this mode, |
1055 | and the caller can be asked to leave it and call again by returning | 1055 | and the caller can be asked to leave it and call again by returning |
1056 | -ECHILD. | 1056 | -ECHILD. -EISDIR may also be returned to tell pathwalk to |
1057 | ignore d_automount or any mounts. | ||
1057 | 1058 | ||
1058 | This function is only used if DCACHE_MANAGE_TRANSIT is set on the | 1059 | This function is only used if DCACHE_MANAGE_TRANSIT is set on the |
1059 | dentry being transited from. | 1060 | dentry being transited from. |