diff options
Diffstat (limited to 'Documentation/filesystems/porting.rst')
| -rw-r--r-- | Documentation/filesystems/porting.rst | 31 |
1 files changed, 27 insertions, 4 deletions
diff --git a/Documentation/filesystems/porting.rst b/Documentation/filesystems/porting.rst index 1be76ef117b3..1639e78e3146 100644 --- a/Documentation/filesystems/porting.rst +++ b/Documentation/filesystems/porting.rst @@ -177,7 +177,7 @@ settles down a bit. **mandatory** s_export_op is now required for exporting a filesystem. -isofs, ext2, ext3, reiserfs, fat +isofs, ext2, ext3, fat can be used as examples of very different filesystems. --- @@ -313,7 +313,7 @@ done. **mandatory** -block truncatation on error exit from ->write_begin, and ->direct_IO +block truncation on error exit from ->write_begin, and ->direct_IO moved from generic methods (block_write_begin, cont_write_begin, nobh_write_begin, blockdev_direct_IO*) to callers. Take a look at ext2_write_failed and callers for an example. @@ -858,7 +858,7 @@ be misspelled d_alloc_anon(). **mandatory** -[should've been added in 2016] stale comment in finish_open() nonwithstanding, +[should've been added in 2016] stale comment in finish_open() notwithstanding, failure exits in ->atomic_open() instances should *NOT* fput() the file, no matter what. Everything is handled by the caller. @@ -989,7 +989,7 @@ This mechanism would only work for a single device so the block layer couldn't find the owning superblock of any additional devices. In the old mechanism reusing or creating a superblock for a racing mount(2) and -umount(2) relied on the file_system_type as the holder. This was severly +umount(2) relied on the file_system_type as the holder. This was severely underdocumented however: (1) Any concurrent mounter that managed to grab an active reference on an @@ -1134,3 +1134,26 @@ 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. + +--- + +**mandatory** + +set_blocksize() takes opened struct file instead of struct block_device now +and it *must* be opened exclusive. + +--- + +** mandatory** + +->d_revalidate() gets two extra arguments - inode of parent directory and +name our dentry is expected to have. Both are stable (dir is pinned in +non-RCU case and will stay around during the call in RCU case, and name +is guaranteed to stay unchanging). Your instance doesn't have to use +either, but it often helps to avoid a lot of painful boilerplate. +Note that while name->name is stable and NUL-terminated, it may (and +often will) have name->name[name->len] equal to '/' rather than '\0' - +in normal case it points into the pathname being looked up. +NOTE: if you need something like full path from the root of filesystem, +you are still on your own - this assists with simple cases, but it's not +magic. |