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Diffstat (limited to 'Documentation/filesystems/porting.rst')
| -rw-r--r-- | Documentation/filesystems/porting.rst | 41 |
1 files changed, 40 insertions, 1 deletions
diff --git a/Documentation/filesystems/porting.rst b/Documentation/filesystems/porting.rst index d890ef07a9fd..1be76ef117b3 100644 --- a/Documentation/filesystems/porting.rst +++ b/Documentation/filesystems/porting.rst @@ -1066,6 +1066,33 @@ 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. + +--- + +**mandatory** + +lock_rename() and lock_rename_child() may fail in cross-directory case, if +their arguments do not have a common ancestor. In that case ERR_PTR(-EXDEV) +is returned, with no locks taken. In-tree users updated; out-of-tree ones +would need to do so. + +--- + +**mandatory** + The list of children anchored in parent dentry got turned into hlist now. Field names got changed (->d_children/->d_sib instead of ->d_subdirs/->d_child for anchor/entries resp.), so any affected places will be immediately caught @@ -1079,7 +1106,7 @@ by compiler. and refcount equal to 0. They are not permitted to drop/regain ->d_lock. None of in-tree instances did anything of that sort. Make sure yours do not... --- +--- **mandatory** @@ -1095,3 +1122,15 @@ Anyone iterating through the list of children needs to be aware of the half-killed dentries that might be seen there; taking ->d_lock on those will see them negative, unhashed and with negative refcount, which means that most of the in-kernel users would've done the right thing anyway without any adjustment. + +--- + +**recommended** + +Block device freezing and thawing have been moved to holder operations. + +Before this change, get_active_super() would only be able to find the +superblock of the main block device, i.e., the one stored in sb->s_bdev. Block +device freezing now works for any block device owned by a given superblock, not +just the main block device. The get_active_super() helper and bd_fsfreeze_sb +pointer are gone. |