Merge remote-tracking branch 'stable/linux-6.7.y' into v6.7+

Author: xdevs23

Documentation/ABI/testing/sysfs-class-devfreq

@@ -52,6 +52,9 @@ Description:
 
 			echo 0 > /sys/class/devfreq/.../trans_stat
 
+		If the transition table is bigger than PAGE_SIZE, reading
+		this will return an -EFBIG error.
+
 What:		/sys/class/devfreq/.../available_frequencies
 Date:		October 2012
 Contact:	Nishanth Menon <[email protected]>

Documentation/admin-guide/abi-obsolete.rst

@@ -7,5 +7,5 @@ marked to be removed at some later point in time.
 The description of the interface will document the reason why it is
 obsolete and when it can be expected to be removed.
 
-.. kernel-abi:: $srctree/Documentation/ABI/obsolete
+.. kernel-abi:: ABI/obsolete
    :rst:

Documentation/admin-guide/abi-removed.rst

@@ -1,5 +1,5 @@
 ABI removed symbols
 ===================
 
-.. kernel-abi:: $srctree/Documentation/ABI/removed
+.. kernel-abi:: ABI/removed
    :rst:

Documentation/admin-guide/abi-stable.rst

@@ -10,5 +10,5 @@ for at least 2 years.
 Most interfaces (like syscalls) are expected to never change and always
 be available.
 
-.. kernel-abi:: $srctree/Documentation/ABI/stable
+.. kernel-abi:: ABI/stable
    :rst:

Documentation/admin-guide/abi-testing.rst

@@ -16,5 +16,5 @@ Programs that use these interfaces are strongly encouraged to add their
 name to the description of these interfaces, so that the kernel
 developers can easily notify them if any changes occur.
 
-.. kernel-abi:: $srctree/Documentation/ABI/testing
+.. kernel-abi:: ABI/testing
    :rst:

Documentation/arch/arm64/silicon-errata.rst

@@ -71,6 +71,8 @@ stable kernels.
 +----------------+-----------------+-----------------+-----------------------------+
 | ARM            | Cortex-A510     | #2658417        | ARM64_ERRATUM_2658417       |
 +----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A510     | #3117295        | ARM64_ERRATUM_3117295       |
++----------------+-----------------+-----------------+-----------------------------+
 | ARM            | Cortex-A520     | #2966298        | ARM64_ERRATUM_2966298       |
 +----------------+-----------------+-----------------+-----------------------------+
 | ARM            | Cortex-A53      | #826319         | ARM64_ERRATUM_826319        |

Documentation/filesystems/directory-locking.rst

@@ -22,13 +22,16 @@ exclusive.
 3) object removal.  Locking rules: caller locks parent, finds victim,
 locks victim and calls the method.  Locks are exclusive.
 
-4) rename() that is _not_ cross-directory.  Locking rules: caller locks the
-parent and finds source and target.  We lock both (provided they exist).  If we
-need to lock two inodes of different type (dir vs non-dir), we lock directory
-first.  If we need to lock two inodes of the same type, lock them in inode
-pointer order.  Then call the method.  All locks are exclusive.
-NB: we might get away with locking the source (and target in exchange
-case) shared.
+4) rename() that is _not_ cross-directory.  Locking rules: caller locks
+the parent and finds source and target.  Then we decide which of the
+source and target need to be locked.  Source needs to be locked if it's a
+non-directory; target - if it's a non-directory or about to be removed.
+Take the locks that need to be taken, in inode pointer order if need
+to take both (that can happen only when both source and target are
+non-directories - the source because it wouldn't be locked otherwise
+and the target because mixing directory and non-directory is allowed
+only with RENAME_EXCHANGE, and that won't be removing the target).
+After the locks had been taken, call the method.  All locks are exclusive.
 
 5) link creation.  Locking rules:
 
@@ -44,20 +47,17 @@ rules:
 
 	* lock the filesystem
 	* lock parents in "ancestors first" order. If one is not ancestor of
-	  the other, lock them in inode pointer order.
+	  the other, lock the parent of source first.
 	* find source and target.
 	* if old parent is equal to or is a descendent of target
 	  fail with -ENOTEMPTY
 	* if new parent is equal to or is a descendent of source
 	  fail with -ELOOP
-	* Lock both the source and the target provided they exist. If we
-	  need to lock two inodes of different type (dir vs non-dir), we lock
-	  the directory first. If we need to lock two inodes of the same type,
-	  lock them in inode pointer order.
+	* Lock subdirectories involved (source before target).
+	* Lock non-directories involved, in inode pointer order.
 	* call the method.
 
-All ->i_rwsem are taken exclusive.  Again, we might get away with locking
-the source (and target in exchange case) shared.
+All ->i_rwsem are taken exclusive.
 
 The rules above obviously guarantee that all directories that are going to be
 read, modified or removed by method will be locked by caller.
@@ -67,6 +67,7 @@ If no directory is its own ancestor, the scheme above is deadlock-free.
 
 Proof:
 
+[XXX: will be updated once we are done massaging the lock_rename()]
 	First of all, at any moment we have a linear ordering of the
 	objects - A < B iff (A is an ancestor of B) or (B is not an ancestor
         of A and ptr(A) < ptr(B)).

Documentation/filesystems/locking.rst

@@ -101,7 +101,7 @@ symlink:	exclusive
 mkdir:		exclusive
 unlink:		exclusive (both)
 rmdir:		exclusive (both)(see below)
-rename:		exclusive (all)	(see below)
+rename:		exclusive (both parents, some children)	(see below)
 readlink:	no
 get_link:	no
 setattr:	exclusive
@@ -123,6 +123,9 @@ get_offset_ctx  no
 	Additionally, ->rmdir(), ->unlink() and ->rename() have ->i_rwsem
 	exclusive on victim.
 	cross-directory ->rename() has (per-superblock) ->s_vfs_rename_sem.
+	->unlink() and ->rename() have ->i_rwsem exclusive on all non-directories
+	involved.
+	->rename() has ->i_rwsem exclusive on any subdirectory that changes parent.
 
 See Documentation/filesystems/directory-locking.rst for more detailed discussion
 of the locking scheme for directory operations.

Documentation/filesystems/overlayfs.rst

@@ -145,7 +145,9 @@ filesystem, an overlay filesystem needs to record in the upper filesystem
 that files have been removed.  This is done using whiteouts and opaque
 directories (non-directories are always opaque).
 
-A whiteout is created as a character device with 0/0 device number.
+A whiteout is created as a character device with 0/0 device number or
+as a zero-size regular file with the xattr "trusted.overlay.whiteout".
+
 When a whiteout is found in the upper level of a merged directory, any
 matching name in the lower level is ignored, and the whiteout itself
 is also hidden.
@@ -154,6 +156,13 @@ A directory is made opaque by setting the xattr "trusted.overlay.opaque"
 to "y".  Where the upper filesystem contains an opaque directory, any
 directory in the lower filesystem with the same name is ignored.
 
+An opaque directory should not conntain any whiteouts, because they do not
+serve any purpose.  A merge directory containing regular files with the xattr
+"trusted.overlay.whiteout", should be additionally marked by setting the xattr
+"trusted.overlay.opaque" to "x" on the merge directory itself.
+This is needed to avoid the overhead of checking the "trusted.overlay.whiteout"
+on all entries during readdir in the common case.
+
 readdir
 -------
 
@@ -534,8 +543,9 @@ A lower dir with a regular whiteout will always be handled by the overlayfs
 mount, so to support storing an effective whiteout file in an overlayfs mount an
 alternative form of whiteout is supported. This form is a regular, zero-size
 file with the "overlay.whiteout" xattr set, inside a directory with the
-"overlay.whiteouts" xattr set. Such whiteouts are never created by overlayfs,
-but can be used by userspace tools (like containers) that generate lower layers.
+"overlay.opaque" xattr set to "x" (see `whiteouts and opaque directories`_).
+These alternative whiteouts are never created by overlayfs, but can be used by
+userspace tools (like containers) that generate lower layers.
 These alternative whiteouts can be escaped using the standard xattr escape
 mechanism in order to properly nest to any depth.
 

Documentation/filesystems/porting.rst

@@ -1061,3 +1061,21 @@ export_operations ->encode_fh() no longer has a default implementation to
 encode FILEID_INO32_GEN* file handles.
 Filesystems that used the default implementation may use the generic helper
 generic_encode_ino32_fh() explicitly.
+
+---
+
+**mandatory**
+
+If ->rename() update of .. on cross-directory move needs an exclusion with
+directory modifications, do *not* lock the subdirectory in question in your
+->rename() - it's done by the caller now [that item should've been added in
+28eceeda130f "fs: Lock moved directories"].
+
+---
+
+**mandatory**
+
+On same-directory ->rename() the (tautological) update of .. is not protected
+by any locks; just don't do it if the old parent is the same as the new one.
+We really can't lock two subdirectories in same-directory rename - not without
+deadlocks.