Merge tag 'vfs-6.12.misc' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs
Pull misc vfs updates from Christian Brauner:
"This contains the usual pile of misc updates:
Features:
- Add F_CREATED_QUERY fcntl() that allows userspace to query whether
a file was actually created. Often userspace wants to know whether
an O_CREATE request did actually create a file without using
O_EXCL. The current logic is that to first attempts to open the
file without O_CREAT | O_EXCL and if ENOENT is returned userspace
tries again with both flags. If that succeeds all is well. If it
now reports EEXIST it retries.
That works fairly well but some corner cases make this more
involved. If this operates on a dangling symlink the first openat()
without O_CREAT | O_EXCL will return ENOENT but the second openat()
with O_CREAT | O_EXCL will fail with EEXIST.
The reason is that openat() without O_CREAT | O_EXCL follows the
symlink while O_CREAT | O_EXCL doesn't for security reasons. So
it's not something we can really change unless we add an explicit
opt-in via O_FOLLOW which seems really ugly.
All available workarounds are really nasty (fanotify, bpf lsm etc)
so add a simple fcntl().
- Try an opportunistic lookup for O_CREAT. Today, when opening a file
we'll typically do a fast lookup, but if O_CREAT is set, the kernel
always takes the exclusive inode lock. This was likely done with
the expectation that O_CREAT means that we always expect to do the
create, but that's often not the case. Many programs set O_CREAT
even in scenarios where the file already exists (see related
F_CREATED_QUERY patch motivation above).
The series contained in the pr rearranges the pathwalk-for-open
code to also attempt a fast_lookup in certain O_CREAT cases. If a
positive dentry is found, the inode_lock can be avoided altogether
and it can stay in rcuwalk mode for the last step_into.
- Expose the 64 bit mount id via name_to_handle_at()
Now that we provide a unique 64-bit mount ID interface in statx(2),
we can now provide a race-free way for name_to_handle_at(2) to
provide a file handle and corresponding mount without needing to
worry about racing with /proc/mountinfo parsing or having to open a
file just to do statx(2).
While this is not necessary if you are using AT_EMPTY_PATH and
don't care about an extra statx(2) call, users that pass full paths
into name_to_handle_at(2) need to know which mount the file handle
comes from (to make sure they don't try to open_by_handle_at a file
handle from a different filesystem) and switching to AT_EMPTY_PATH
would require allocating a file for every name_to_handle_at(2) call
- Add a per dentry expire timeout to autofs
There are two fairly well known automounter map formats, the autofs
format and the amd format (more or less System V and Berkley).
Some time ago Linux autofs added an amd map format parser that
implemented a fair amount of the amd functionality. This was done
within the autofs infrastructure and some functionality wasn't
implemented because it either didn't make sense or required extra
kernel changes. The idea was to restrict changes to be within the
existing autofs functionality as much as possible and leave changes
with a wider scope to be considered later.
One of these changes is implementing the amd options:
1) "unmount", expire this mount according to a timeout (same as
the current autofs default).
2) "nounmount", don't expire this mount (same as setting the
autofs timeout to 0 except only for this specific mount) .
3) "utimeout=<seconds>", expire this mount using the specified
timeout (again same as setting the autofs timeout but only for
this mount)
To implement these options per-dentry expire timeouts need to be
implemented for autofs indirect mounts. This is because all map
keys (mounts) for autofs indirect mounts use an expire timeout
stored in the autofs mount super block info. structure and all
indirect mounts use the same expire timeout.
Fixes:
- Fix missing fput for FSCONFIG_SET_FD in autofs
- Use param->file for FSCONFIG_SET_FD in coda
- Delete the 'fs/netfs' proc subtreee when netfs module exits
- Make sure that struct uid_gid_map fits into a single cacheline
- Don't flush in-flight wb switches for superblocks without cgroup
writeback
- Correcting the idmapping mount example in the idmapping
documentation
- Fix a race between evice_inodes() and find_inode() and iput()
- Refine the show_inode_state() macro definition in writeback code
- Prevent dump_mapping() from accessing invalid dentry.d_name.name
- Show actual source for debugfs in /proc/mounts
- Annotate data-race of busy_poll_usecs in eventpoll
- Don't WARN for racy path_noexec check in exec code
- Handle OOM on mnt_warn_timestamp_expiry()
- Fix some spelling in the iomap design documentation
- Fix typo in procfs comment
- Fix typo in fs/namespace.c comment
Cleanups:
- Add the VFS git tree to the MAINTAINERS file
- Move FMODE_UNSIGNED_OFFSET to fop_flags freeing up another f_mode
bit in struct file bringing us to 5 free f_mode bits
- Remove the __I_DIO_WAKEUP bit from i_state flags as we can simplify
the wait mechanism
- Remove the unused path_put_init() helper
- Replace a __u32 with u32 for s_fsnotify_mask as __u32 is uapi
specific
- Replace the unsigned long i_state member with a u32 i_state member
in struct inode freeing up 4 bytes in struct inode. Instead of
using the bit based wait apis we're now using the var event apis
and using the individual bytes of the i_state member to wait on
state changes
- Explain how per-syscall AT_* flags should be allocated
- Use in_group_or_capable() helper to simplify the posix acl mode
update code
- Switch to LIST_HEAD() in fsync_buffers_list() to simplify the code
- Removed comment about d_rcu_to_refcount() as that function doesn't
exist anymore
- Add kernel documentation for lookup_fast()
- Don't re-zero evenpoll fields
- Remove outdated comment after close_fd()
- Fix imprecise wording in comment about the pipe filesystem
- Drop GFP_NOFAIL mode from alloc_page_buffers
- Missing blank line warnings and struct declaration improved in
file_table
- Annotate struct poll_list with __counted_by()
- Remove the unused read parameter in percpu-rwsem
- Remove linux/prefetch.h include from direct-io code
- Use kmemdup_array instead of kmemdup for multiple allocation in
mnt_idmapping code
- Remove unused mnt_cursor_del() declaration
Performance tweaks:
- Dodge smp_mb in break_lease and break_deleg in the common case
- Only read fops once in fops_{get,put}()
- Use RCU in ilookup()
- Elide smp_mb in iversion handling in the common case
- Drop one lock trip in evict()"
* tag 'vfs-6.12.misc' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs: (58 commits)
uidgid: make sure we fit into one cacheline
proc: Fix typo in the comment
fs/pipe: Correct imprecise wording in comment
fhandle: expose u64 mount id to name_to_handle_at(2)
uapi: explain how per-syscall AT_* flags should be allocated
fs: drop GFP_NOFAIL mode from alloc_page_buffers
writeback: Refine the show_inode_state() macro definition
fs/inode: Prevent dump_mapping() accessing invalid dentry.d_name.name
mnt_idmapping: Use kmemdup_array instead of kmemdup for multiple allocation
netfs: Delete subtree of 'fs/netfs' when netfs module exits
fs: use LIST_HEAD() to simplify code
inode: make i_state a u32
inode: port __I_LRU_ISOLATING to var event
vfs: fix race between evice_inodes() and find_inode()&iput()
inode: port __I_NEW to var event
inode: port __I_SYNC to var event
fs: reorder i_state bits
fs: add i_state helpers
MAINTAINERS: add the VFS git tree
fs: s/__u32/u32/ for s_fsnotify_mask
...
This commit is contained in:
Linus Torvalds
@@ -23,7 +23,7 @@
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#define AUTOFS_MIN_PROTO_VERSION 3
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#define AUTOFS_MAX_PROTO_VERSION 5
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#define AUTOFS_PROTO_SUBVERSION 5
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#define AUTOFS_PROTO_SUBVERSION 6
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/*
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* The wait_queue_token (autofs_wqt_t) is part of a structure which is passed
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+60
-24
@@ -16,6 +16,9 @@
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#define F_DUPFD_QUERY (F_LINUX_SPECIFIC_BASE + 3)
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/* Was the file just created? */
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#define F_CREATED_QUERY (F_LINUX_SPECIFIC_BASE + 4)
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/*
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* Cancel a blocking posix lock; internal use only until we expose an
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* asynchronous lock api to userspace:
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@@ -87,37 +90,70 @@
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#define DN_ATTRIB 0x00000020 /* File changed attibutes */
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#define DN_MULTISHOT 0x80000000 /* Don't remove notifier */
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#define AT_FDCWD -100 /* Special value for dirfd used to
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indicate openat should use the
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current working directory. */
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/* Generic flags for the *at(2) family of syscalls. */
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/* Reserved for per-syscall flags 0xff. */
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#define AT_SYMLINK_NOFOLLOW 0x100 /* Do not follow symbolic
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links. */
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/* Reserved for per-syscall flags 0x200 */
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#define AT_SYMLINK_FOLLOW 0x400 /* Follow symbolic links. */
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#define AT_NO_AUTOMOUNT 0x800 /* Suppress terminal automount
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traversal. */
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#define AT_EMPTY_PATH 0x1000 /* Allow empty relative
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pathname to operate on dirfd
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directly. */
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/*
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* The constants AT_REMOVEDIR and AT_EACCESS have the same value. AT_EACCESS is
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* meaningful only to faccessat, while AT_REMOVEDIR is meaningful only to
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* unlinkat. The two functions do completely different things and therefore,
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* the flags can be allowed to overlap. For example, passing AT_REMOVEDIR to
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* faccessat would be undefined behavior and thus treating it equivalent to
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* AT_EACCESS is valid undefined behavior.
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* These flags are currently statx(2)-specific, but they could be made generic
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* in the future and so they should not be used for other per-syscall flags.
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*/
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#define AT_FDCWD -100 /* Special value used to indicate
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openat should use the current
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working directory. */
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#define AT_SYMLINK_NOFOLLOW 0x100 /* Do not follow symbolic links. */
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#define AT_STATX_SYNC_TYPE 0x6000 /* Type of synchronisation required from statx() */
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#define AT_STATX_SYNC_AS_STAT 0x0000 /* - Do whatever stat() does */
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#define AT_STATX_FORCE_SYNC 0x2000 /* - Force the attributes to be sync'd with the server */
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#define AT_STATX_DONT_SYNC 0x4000 /* - Don't sync attributes with the server */
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#define AT_RECURSIVE 0x8000 /* Apply to the entire subtree */
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/*
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* Per-syscall flags for the *at(2) family of syscalls.
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*
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* These are flags that are so syscall-specific that a user passing these flags
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* to the wrong syscall is so "clearly wrong" that we can safely call such
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* usage "undefined behaviour".
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*
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* For example, the constants AT_REMOVEDIR and AT_EACCESS have the same value.
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* AT_EACCESS is meaningful only to faccessat, while AT_REMOVEDIR is meaningful
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* only to unlinkat. The two functions do completely different things and
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* therefore, the flags can be allowed to overlap. For example, passing
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* AT_REMOVEDIR to faccessat would be undefined behavior and thus treating it
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* equivalent to AT_EACCESS is valid undefined behavior.
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*
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* Note for implementers: When picking a new per-syscall AT_* flag, try to
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* reuse already existing flags first. This leaves us with as many unused bits
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* as possible, so we can use them for generic bits in the future if necessary.
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*/
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/* Flags for renameat2(2) (must match legacy RENAME_* flags). */
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#define AT_RENAME_NOREPLACE 0x0001
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#define AT_RENAME_EXCHANGE 0x0002
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#define AT_RENAME_WHITEOUT 0x0004
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/* Flag for faccessat(2). */
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#define AT_EACCESS 0x200 /* Test access permitted for
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effective IDs, not real IDs. */
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/* Flag for unlinkat(2). */
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#define AT_REMOVEDIR 0x200 /* Remove directory instead of
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unlinking file. */
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#define AT_SYMLINK_FOLLOW 0x400 /* Follow symbolic links. */
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#define AT_NO_AUTOMOUNT 0x800 /* Suppress terminal automount traversal */
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#define AT_EMPTY_PATH 0x1000 /* Allow empty relative pathname */
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/* Flags for name_to_handle_at(2). */
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#define AT_HANDLE_FID 0x200 /* File handle is needed to compare
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object identity and may not be
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usable with open_by_handle_at(2). */
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#define AT_HANDLE_MNT_ID_UNIQUE 0x001 /* Return the u64 unique mount ID. */
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#define AT_STATX_SYNC_TYPE 0x6000 /* Type of synchronisation required from statx() */
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#define AT_STATX_SYNC_AS_STAT 0x0000 /* - Do whatever stat() does */
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#define AT_STATX_FORCE_SYNC 0x2000 /* - Force the attributes to be sync'd with the server */
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#define AT_STATX_DONT_SYNC 0x4000 /* - Don't sync attributes with the server */
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#define AT_RECURSIVE 0x8000 /* Apply to the entire subtree */
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/* Flags for name_to_handle_at(2). We reuse AT_ flag space to save bits... */
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#define AT_HANDLE_FID AT_REMOVEDIR /* file handle is needed to
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compare object identity and may not
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be usable to open_by_handle_at(2) */
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#if defined(__KERNEL__)
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#define AT_GETATTR_NOSEC 0x80000000
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#endif
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