kernel.git/Documentation/filesystems/porting, branch linux-4.19.y

cifs_atomic_open(): fix double-put on late allocation failure

2020-03-18T06:14:21Z

commit d9a9f4849fe0c9d560851ab22a85a666cddfdd24 upstream. several iterations of ->atomic_open() calling conventions ago, we used to need fput() if ->atomic_open() failed at some point after successful finish_open(). Now (since 2016) it's not needed - struct file carries enough state to make fput() work regardless of the point in struct file lifecycle and discarding it on failure exits in open() got unified. Unfortunately, I'd missed the fact that we had an instance of ->atomic_open() (cifs one) that used to need that fput(), as well as the stale comment in finish_open() demanding such late failure handling. Trivially fixed... Fixes: fe9ec8291fca "do_last(): take fput() on error after opening to out:" Cc: stable@kernel.org # v4.7+ Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman

dcache: sort the freeing-without-RCU-delay mess for good.

2019-05-25T16:23:26Z

commit 5467a68cbf6884c9a9d91e2a89140afb1839c835 upstream. For lockless accesses to dentries we don't have pinned we rely (among other things) upon having an RCU delay between dropping the last reference and actually freeing the memory. On the other hand, for things like pipes and sockets we neither do that kind of lockless access, nor want to deal with the overhead of an RCU delay every time a socket gets closed. So delay was made optional - setting DCACHE_RCUACCESS in ->d_flags made sure it would happen. We tried to avoid setting it unless we knew we need it. Unfortunately, that had led to recurring class of bugs, in which we missed the need to set it. We only really need it for dentries that are created by d_alloc_pseudo(), so let's not bother with trying to be smart - just make having an RCU delay the default. The ones that do *not* get it set the replacement flag (DCACHE_NORCU) and we'd better use that sparingly. d_alloc_pseudo() is the only such user right now. FWIW, the race that finally prompted that switch had been between __lock_parent() of immediate subdirectory of what's currently the root of a disconnected tree (e.g. from open-by-handle in progress) racing with d_splice_alias() elsewhere picking another alias for the same inode, either on outright corrupted fs image, or (in case of open-by-handle on NFS) that subdirectory having been just moved on server. It's not easy to hit, so the sky is not falling, but that's not the first race on similar missed cases and the logics for settinf DCACHE_RCUACCESS has gotten ridiculously convoluted. Cc: stable@vger.kernel.org Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman

document alloc_file() changes

2018-07-12T14:04:29Z

Acked-by: Linus Torvalds Signed-off-by: Al Viro

document ->atomic_open() changes

2018-07-12T14:04:22Z

Acked-by: Linus Torvalds Signed-off-by: Al Viro

vfs: grab the lock instead of blocking in __fd_install during resizing

2017-11-05T23:58:07Z

Explicit locking in the fallback case provides a safe state of the table. Getting rid of blocking semantics makes __fd_install usable again in non-sleepable contexts, which easies backporting efforts. There is a side effect of slightly nicer assembly for the common case as might_sleep can now be removed. Signed-off-by: Mateusz Guzik Signed-off-by: Al Viro

VFS: Differentiate mount flags (MS_*) from internal superblock flags

2017-07-17T07:45:35Z

Differentiate the MS_* flags passed to mount(2) from the internal flags set in the super_block's s_flags. s_flags are now called SB_*, with the names and the values for the moment mirroring the MS_* flags that they're equivalent to. In this patch, just the headers are altered and some kernel code where blind automated conversion isn't necessarily correct. Note that this shows up some interesting issues: (1) Some MS_* flags get translated to MNT_* flags (such as MS_NODEV -> MNT_NODEV) without passing this on to the filesystem, but some filesystems set such flags anyway. (2) The ->remount_fs() methods of some filesystems adjust the *flags argument by setting MS_* flags in it, such as MS_NOATIME - but these flags are then scrubbed by do_remount_sb() (only the occupants of MS_RMT_MASK are permitted: MS_RDONLY, MS_SYNCHRONOUS, MS_MANDLOCK, MS_I_VERSION and MS_LAZYTIME) I'm not sure what's the best way to solve all these cases. Suggested-by: Al Viro Signed-off-by: David Howells

Documentation/filesystems: fix documentation for ->getattr()

2017-04-03T05:05:56Z

Following the recent merge of statx, correct the documented prototype for the ->getattr() inode operation, and add an entry to the porting file. Signed-off-by: Eric Biggers Signed-off-by: David Howells Signed-off-by: Al Viro

vfs: default to generic_readlink()

2016-12-09T15:45:04Z

If i_op->readlink is NULL, but i_op->get_link is set then vfs_readlink() defaults to calling generic_readlink(). The IOP_DEFAULT_READLINK flag indicates that the above conditions are met and the default action can be taken. Signed-off-by: Miklos Szeredi

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2016-10-11T03:16:43Z

Pull more vfs updates from Al Viro: ">rename2() work from Miklos + current_time() from Deepa" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: fs: Replace current_fs_time() with current_time() fs: Replace CURRENT_TIME_SEC with current_time() for inode timestamps fs: Replace CURRENT_TIME with current_time() for inode timestamps fs: proc: Delete inode time initializations in proc_alloc_inode() vfs: Add current_time() api vfs: add note about i_op->rename changes to porting fs: rename "rename2" i_op to "rename" vfs: remove unused i_op->rename fs: make remaining filesystems use .rename2 libfs: support RENAME_NOREPLACE in simple_rename() fs: support RENAME_NOREPLACE for local filesystems ncpfs: fix unused variable warning

vfs: add note about i_op->rename changes to porting

2016-09-27T09:03:58Z

Signed-off-by: Miklos Szeredi