Added/updated descriptions for super_operations:
- free_inode method
- evict_inode method
- freeze_super/thaw_super method
- show_{devname,path,stats} procfs-related methods
- get_dquots method
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: linux-fsdevel@xxxxxxxxxxxxxxx
Cc: linux-doc@xxxxxxxxxxxxxxx
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@xxxxxxxxxxxxx>
---
Documentation/filesystems/vfs.rst | 74 ++++++++++++++++++++++++-------
1 file changed, 59 insertions(+), 15 deletions(-)
diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst
index 113d70186324..e906867e3e83 100644
--- a/Documentation/filesystems/vfs.rst
+++ b/Documentation/filesystems/vfs.rst
@@ -245,33 +245,42 @@ struct super_operations
-----------------------
This describes how the VFS can manipulate the superblock of your
-filesystem. As of kernel 2.6.22, the following members are defined:
+filesystem. As of kernel 6.1, the following members are defined:
.. code-block:: c
struct super_operations {
struct inode *(*alloc_inode)(struct super_block *sb);
void (*destroy_inode)(struct inode *);
+ void (*free_inode)(struct inode *);
void (*dirty_inode) (struct inode *, int flags);
- int (*write_inode) (struct inode *, int);
- void (*drop_inode) (struct inode *);
- void (*delete_inode) (struct inode *);
+ int (*write_inode) (struct inode *, struct writeback_control *wbc);
+ int (*drop_inode) (struct inode *);
+ void (*evict_inode) (struct inode *);
void (*put_super) (struct super_block *);
int (*sync_fs)(struct super_block *sb, int wait);
+ int (*freeze_super) (struct super_block *);
int (*freeze_fs) (struct super_block *);
+ int (*thaw_super) (struct super_block *);
int (*unfreeze_fs) (struct super_block *);
int (*statfs) (struct dentry *, struct kstatfs *);
int (*remount_fs) (struct super_block *, int *, char *);
- void (*clear_inode) (struct inode *);
void (*umount_begin) (struct super_block *);
int (*show_options)(struct seq_file *, struct dentry *);
+ int (*show_devname)(struct seq_file *, struct dentry *);
+ int (*show_path)(struct seq_file *, struct dentry *);
+ int (*show_stats)(struct seq_file *, struct dentry *);
ssize_t (*quota_read)(struct super_block *, int, char *, size_t, loff_t);
ssize_t (*quota_write)(struct super_block *, int, const char *, size_t, loff_t);
- int (*nr_cached_objects)(struct super_block *);
- void (*free_cached_objects)(struct super_block *, int);
+ struct dquot **(*get_dquots)(struct inode *);
+
+ long (*nr_cached_objects)(struct super_block *,
+ struct shrink_control *);
+ long (*free_cached_objects)(struct super_block *,
+ struct shrink_control *);
};
All methods are called without any locks being held, unless otherwise
@@ -292,6 +301,11 @@ or bottom half).
->alloc_inode was defined and simply undoes anything done by
->alloc_inode.
+``free_inode``
+ this method is called from RCU callback. If you use call_rcu()
+ in ->destroy_inode to free 'struct inode' memory, then it's
+ better to release memory in this method.
+
``dirty_inode``
this method is called by the VFS when an inode is marked dirty.
This is specifically for the inode itself being marked dirty,
@@ -319,8 +333,12 @@ or bottom half).
practice of using "force_delete" in the put_inode() case, but
does not have the races that the "force_delete()" approach had.
-``delete_inode``
- called when the VFS wants to delete an inode
+``evict_inode``
+ called when the VFS wants to evict an inode. Caller does
+ *not* evict the pagecache or inode-associated metadata buffers;
+ the method has to use truncate_inode_pages_final() to get rid
+ of those. Caller makes sure async writeback cannot be running for
+ the inode while (or after) ->evict_inode() is called. Optional.
``put_super``
called when the VFS wishes to free the superblock
@@ -331,14 +349,25 @@ or bottom half).
superblock. The second parameter indicates whether the method
should wait until the write out has been completed. Optional.
+``freeze_super``
+ Called instead of ->freeze_fs callback if provided.
+ Main difference is that ->freeze_super is called without taking
+ down_write(&sb->s_umount). If filesystem implements it and wants
+ ->freeze_fs to be called too, then it has to call ->freeze_fs
+ explicitly from this callback. Optional.
+
``freeze_fs``
called when VFS is locking a filesystem and forcing it into a
consistent state. This method is currently used by the Logical
- Volume Manager (LVM).
+ Volume Manager (LVM) and ioctl(FIFREEZE). Optional.
+
+``thaw_super``
+ called when VFS is unlocking a filesystem and making it writable
+ again after ->freeze_super. Optional.
``unfreeze_fs``
called when VFS is unlocking a filesystem and making it writable
- again.
+ again after ->freeze_fs. Optional.
``statfs``
called when the VFS needs to get filesystem statistics.
@@ -347,22 +376,37 @@ or bottom half).
called when the filesystem is remounted. This is called with
the kernel lock held
-``clear_inode``
- called then the VFS clears the inode. Optional
-
``umount_begin``
called when the VFS is unmounting a filesystem.
``show_options``
- called by the VFS to show mount options for /proc/<pid>/mounts.
+ called by the VFS to show mount options for /proc/<pid>/mounts
+ and /proc/<pid>/mountinfo.
(see "Mount Options" section)
+``show_devname``
+ Optional. Called by the VFS to show device name for
+ /proc/<pid>/{mounts,mountinfo,mountstats}. If not provided then
+ '(struct mount).mnt_devname' will be used.
+
+``show_path``
+ Optional. Called by the VFS (for /proc/<pid>/mountinfo) to show
+ the mount root dentry path relative to the filesystem root.
+
+``show_stats``
+ Optional. Called by the VFS (for /proc/<pid>/mountstats) to show
+ filesystem-specific mount statistics.
+
``quota_read``
called by the VFS to read from filesystem quota file.
``quota_write``
called by the VFS to write to filesystem quota file.
+``get_dquots``
+ called by quota to get 'struct dquot' array for a particular inode.
+ Optional.
+
``nr_cached_objects``
called by the sb cache shrinking function for the filesystem to
return the number of freeable cached objects it contains.
--
2.34.1
