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Diffstat (limited to 'Documentation/filesystems/porting.rst')
| -rw-r--r-- | Documentation/filesystems/porting.rst | 48 |
1 files changed, 45 insertions, 3 deletions
diff --git a/Documentation/filesystems/porting.rst b/Documentation/filesystems/porting.rst index 3111ef5592f3..85f590254f07 100644 --- a/Documentation/filesystems/porting.rst +++ b/Documentation/filesystems/porting.rst @@ -1224,9 +1224,6 @@ lookup_noperm_unlocked(), lookup_noperm_positive_unlocked(). They now take a qstr instead of separate name and length. QSTR() can be used when strlen() is needed for the length. -For try_lookup_noperm() a reference to the qstr is passed in case the -hash might subsequently be needed. - These function no longer do any permission checking - they previously checked that the caller has 'X' permission on the parent. They must ONLY be used internally by a filesystem on itself when it knows that @@ -1243,3 +1240,48 @@ arguments in the opposite order but is otherwise identical. Using try_lookup_noperm() will require linux/namei.h to be included. +--- + +**mandatory** + +Calling conventions for ->d_automount() have changed; we should *not* grab +an extra reference to new mount - it should be returned with refcount 1. + +--- + +collect_mounts()/drop_collected_mounts()/iterate_mounts() are gone now. +Replacement is collect_paths()/drop_collected_path(), with no special +iterator needed. Instead of a cloned mount tree, the new interface returns +an array of struct path, one for each mount collect_mounts() would've +created. These struct path point to locations in the caller's namespace +that would be roots of the cloned mounts. + +--- + +**mandatory** + +If your filesystem sets the default dentry_operations, use set_default_d_op() +rather than manually setting sb->s_d_op. + +--- + +**mandatory** + +d_set_d_op() is no longer exported (or public, for that matter); _if_ +your filesystem really needed that, make use of d_splice_alias_ops() +to have them set. Better yet, think hard whether you need different +->d_op for different dentries - if not, just use set_default_d_op() +at mount time and be done with that. Currently procfs is the only +thing that really needs ->d_op varying between dentries. + +--- + +**highly recommended** + +The file operations mmap() callback is deprecated in favour of +mmap_prepare(). This passes a pointer to a vm_area_desc to the callback +rather than a VMA, as the VMA at this stage is not yet valid. + +The vm_area_desc provides the minimum required information for a filesystem +to initialise state upon memory mapping of a file-backed region, and output +parameters for the file system to set this state. |