diff options
Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/erofs.rst | 8 | ||||
| -rw-r--r-- | Documentation/filesystems/idmappings.rst | 72 | ||||
| -rw-r--r-- | Documentation/filesystems/locking.rst | 5 |
3 files changed, 8 insertions, 77 deletions
diff --git a/Documentation/filesystems/erofs.rst b/Documentation/filesystems/erofs.rst index 01df283c7d04..7119aa213be7 100644 --- a/Documentation/filesystems/erofs.rst +++ b/Documentation/filesystems/erofs.rst @@ -93,6 +93,14 @@ dax A legacy option which is an alias for ``dax=always``. device=%s Specify a path to an extra device to be used together. =================== ========================================================= +Sysfs Entries +============= + +Information about mounted erofs file systems can be found in /sys/fs/erofs. +Each mounted filesystem will have a directory in /sys/fs/erofs based on its +device name (i.e., /sys/fs/erofs/sda). +(see also Documentation/ABI/testing/sysfs-fs-erofs) + On-disk details =============== diff --git a/Documentation/filesystems/idmappings.rst b/Documentation/filesystems/idmappings.rst index 1229a75ec75d..7a879ec3b6bf 100644 --- a/Documentation/filesystems/idmappings.rst +++ b/Documentation/filesystems/idmappings.rst @@ -952,75 +952,3 @@ The raw userspace id that is put on disk is ``u1000`` so when the user takes their home directory back to their home computer where they are assigned ``u1000`` using the initial idmapping and mount the filesystem with the initial idmapping they will see all those files owned by ``u1000``. - -Shortcircuting --------------- - -Currently, the implementation of idmapped mounts enforces that the filesystem -is mounted with the initial idmapping. The reason is simply that none of the -filesystems that we targeted were mountable with a non-initial idmapping. But -that might change soon enough. As we've seen above, thanks to the properties of -idmappings the translation works for both filesystems mounted with the initial -idmapping and filesystem with non-initial idmappings. - -Based on this current restriction to filesystem mounted with the initial -idmapping two noticeable shortcuts have been taken: - -1. We always stash a reference to the initial user namespace in ``struct - vfsmount``. Idmapped mounts are thus mounts that have a non-initial user - namespace attached to them. - - In order to support idmapped mounts this needs to be changed. Instead of - stashing the initial user namespace the user namespace the filesystem was - mounted with must be stashed. An idmapped mount is then any mount that has - a different user namespace attached then the filesystem was mounted with. - This has no user-visible consequences. - -2. The translation algorithms in ``mapped_fs*id()`` and ``i_*id_into_mnt()`` - are simplified. - - Let's consider ``mapped_fs*id()`` first. This function translates the - caller's kernel id into a kernel id in the filesystem's idmapping via - a mount's idmapping. The full algorithm is:: - - mapped_fsuid(kid): - /* Map the kernel id up into a userspace id in the mount's idmapping. */ - from_kuid(mount-idmapping, kid) = uid - - /* Map the userspace id down into a kernel id in the filesystem's idmapping. */ - make_kuid(filesystem-idmapping, uid) = kuid - - We know that the filesystem is always mounted with the initial idmapping as - we enforce this in ``mount_setattr()``. So this can be shortened to:: - - mapped_fsuid(kid): - /* Map the kernel id up into a userspace id in the mount's idmapping. */ - from_kuid(mount-idmapping, kid) = uid - - /* Map the userspace id down into a kernel id in the filesystem's idmapping. */ - KUIDT_INIT(uid) = kuid - - Similarly, for ``i_*id_into_mnt()`` which translated the filesystem's kernel - id into a mount's kernel id:: - - i_uid_into_mnt(kid): - /* Map the kernel id up into a userspace id in the filesystem's idmapping. */ - from_kuid(filesystem-idmapping, kid) = uid - - /* Map the userspace id down into a kernel id in the mounts's idmapping. */ - make_kuid(mount-idmapping, uid) = kuid - - Again, we know that the filesystem is always mounted with the initial - idmapping as we enforce this in ``mount_setattr()``. So this can be - shortened to:: - - i_uid_into_mnt(kid): - /* Map the kernel id up into a userspace id in the filesystem's idmapping. */ - __kuid_val(kid) = uid - - /* Map the userspace id down into a kernel id in the mounts's idmapping. */ - make_kuid(mount-idmapping, uid) = kuid - -Handling filesystems mounted with non-initial idmappings requires that the -translation functions be converted to their full form. They can still be -shortcircuited on non-idmapped mounts. This has no user-visible consequences. diff --git a/Documentation/filesystems/locking.rst b/Documentation/filesystems/locking.rst index d36fe79167b3..3f9b1497ebb8 100644 --- a/Documentation/filesystems/locking.rst +++ b/Documentation/filesystems/locking.rst @@ -169,7 +169,6 @@ prototypes:: int (*show_options)(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 (*bdev_try_to_free_page)(struct super_block*, struct page*, gfp_t); locking rules: All may block [not true, see below] @@ -194,7 +193,6 @@ umount_begin: no show_options: no (namespace_sem) quota_read: no (see below) quota_write: no (see below) -bdev_try_to_free_page: no (see below) ====================== ============ ======================== ->statfs() has s_umount (shared) when called by ustat(2) (native or @@ -210,9 +208,6 @@ dqio_sem) (unless an admin really wants to screw up something and writes to quota files with quotas on). For other details about locking see also dquot_operations section. -->bdev_try_to_free_page is called from the ->releasepage handler of -the block device inode. See there for more details. - file_system_type ================ |