kernel/linux.git/fs/exportfs, branch master

Merge tag 'pull-dcache-busy-wait' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2026-04-21T14:30:44+00:00

Pull dcache busy loop updates from Al Viro: "Fix livelocks in shrink_dcache_tree() If shrink_dcache_tree() finds a dentry in the middle of being killed by another thread, it has to wait until the victim finishes dying, gets detached from the tree and ceases to pin its parent. The way we used to deal with that amounted to busy-wait; unfortunately, it's not just inefficient but can lead to reliably reproducible hard livelocks. Solved by having shrink_dentry_tree() attach a completion to such dentry, with dentry_unlist() calling complete() on all objects attached to it. With a bit of care it can be done without growing struct dentry or adding overhead in normal case" * tag 'pull-dcache-busy-wait' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: get rid of busy-waiting in shrink_dcache_tree() dcache.c: more idiomatic "positives are not allowed" sanity checks struct dentry: make ->d_u anonymous for_each_alias(): helper macro for iterating through dentries of given inode

for_each_alias(): helper macro for iterating through dentries of given inode

2026-04-02T07:45:02+00:00

Most of the places using d_alias are loops iterating through all aliases for given inode; introduce a helper macro (for_each_alias(dentry, inode)) and convert open-coded instances of such loop to it. They are easier to read that way and it reduces the noise on the next steps. You _must_ hold inode->i_lock over that thing. Signed-off-by: Al Viro

treewide: change inode->i_ino from unsigned long to u64

2026-03-06T13:31:28+00:00

On 32-bit architectures, unsigned long is only 32 bits wide, which causes 64-bit inode numbers to be silently truncated. Several filesystems (NFS, XFS, BTRFS, etc.) can generate inode numbers that exceed 32 bits, and this truncation can lead to inode number collisions and other subtle bugs on 32-bit systems. Change the type of inode->i_ino from unsigned long to u64 to ensure that inode numbers are always represented as 64-bit values regardless of architecture. Update all format specifiers treewide from %lu/%lx to %llu/%llx to match the new type, along with corresponding local variable types. This is the bulk treewide conversion. Earlier patches in this series handled trace events separately to allow trace field reordering for better struct packing on 32-bit. Signed-off-by: Jeff Layton Link: https://patch.msgid.link/20260304-iino-u64-v3-12-2257ad83d372@kernel.org Acked-by: Damien Le Moal Reviewed-by: Christoph Hellwig Reviewed-by: Jan Kara Reviewed-by: Chuck Lever Signed-off-by: Christian Brauner

fs: add helpers name_is_dot{,dot,_dotdot}

2026-01-29T09:06:59+00:00

Rename the helper is_dot_dotdot() into the name_ namespace and add complementary helpers to check for dot and dotdot names individually. Signed-off-by: Amir Goldstein Link: https://patch.msgid.link/20260128132406.23768-3-amir73il@gmail.com Reviewed-by: Eric Biggers Signed-off-by: Christian Brauner

exportfs: use lookup_one_unlocked()

2025-06-11T11:44:15+00:00

rather than locking the directory and using lookup_one(), just use lookup_one_unlocked(). This keeps locking code centralised. Signed-off-by: NeilBrown Link: https://lore.kernel.org/20250608230952.20539-5-neil@brown.name Reviewed-by: Chuck Lever Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner

Merge tag 'vfs-6.16-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2025-05-26T16:02:39+00:00

Pull misc vfs updates from Christian Brauner: "This contains the usual selections of misc updates for this cycle. Features: - Use folios for symlinks in the page cache FUSE already uses folios for its symlinks. Mirror that conversion in the generic code and the NFS code. That lets us get rid of a few folio->page->folio conversions in this path, and some of the few remaining users of read_cache_page() / read_mapping_page() - Try and make a few filesystem operations killable on the VFS inode->i_mutex level - Add sysctl vfs_cache_pressure_denom for bulk file operations Some workloads need to preserve more dentries than we currently allow through out sysctl interface A HDFS servers with 12 HDDs per server, on a HDFS datanode startup involves scanning all files and caching their metadata (including dentries and inodes) in memory. Each HDD contains approximately 2 million files, resulting in a total of ~20 million cached dentries after initialization To minimize dentry reclamation, they set vfs_cache_pressure to 1. Despite this configuration, memory pressure conditions can still trigger reclamation of up to 50% of cached dentries, reducing the cache from 20 million to approximately 10 million entries. During the subsequent cache rebuild period, any HDFS datanode restart operation incurs substantial latency penalties until full cache recovery completes To maintain service stability, more dentries need to be preserved during memory reclamation. The current minimum reclaim ratio (1/100 of total dentries) remains too aggressive for such workload. This patch introduces vfs_cache_pressure_denom for more granular cache pressure control The configuration [vfs_cache_pressure=1, vfs_cache_pressure_denom=10000] effectively maintains the full 20 million dentry cache under memory pressure, preventing datanode restart performance degradation - Avoid some jumps in inode_permission() using likely()/unlikely() - Avid a memory access which is most likely a cache miss when descending into devcgroup_inode_permission() - Add fastpath predicts for stat() and fdput() - Anonymous inodes currently don't come with a proper mode causing issues in the kernel when we want to add useful VFS debug assert. Fix that by giving them a proper mode and masking it off when we report it to userspace which relies on them not having any mode - Anonymous inodes currently allow to change inode attributes because the VFS falls back to simple_setattr() if i_op->setattr isn't implemented. This means the ownership and mode for every single user of anon_inode_inode can be changed. Block that as it's either useless or actively harmful. If specific ownership is needed the respective subsystem should allocate anonymous inodes from their own private superblock - Raise SB_I_NODEV and SB_I_NOEXEC on the anonymous inode superblock - Add proper tests for anonymous inode behavior - Make it easy to detect proper anonymous inodes and to ensure that we can detect them in codepaths such as readahead() Cleanups: - Port pidfs to the new anon_inode_{g,s}etattr() helpers - Try to remove the uselib() system call - Add unlikely branch hint return path for poll - Add unlikely branch hint on return path for core_sys_select - Don't allow signals to interrupt getdents copying for fuse - Provide a size hint to dir_context for during readdir() - Use writeback_iter directly in mpage_writepages - Update compression and mtime descriptions in initramfs documentation - Update main netfs API document - Remove useless plus one in super_cache_scan() - Remove unnecessary NULL-check guards during setns() - Add separate separate {get,put}_cgroup_ns no-op cases Fixes: - Fix typo in root= kernel parameter description - Use KERN_INFO for infof()|info_plog()|infofc() - Correct comments of fs_validate_description() - Mark an unlikely if condition with unlikely() in vfs_parse_monolithic_sep() - Delete macro fsparam_u32hex() - Remove unused and problematic validate_constant_table() - Fix potential unsigned integer underflow in fs_name() - Make file-nr output the total allocated file handles" * tag 'vfs-6.16-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (43 commits) fs: Pass a folio to page_put_link() nfs: Use a folio in nfs_get_link() fs: Convert __page_get_link() to use a folio fs/read_write: make default_llseek() killable fs/open: make do_truncate() killable fs/open: make chmod_common() and chown_common() killable include/linux/fs.h: add inode_lock_killable() readdir: supply dir_context.count as readdir buffer size hint vfs: Add sysctl vfs_cache_pressure_denom for bulk file operations fuse: don't allow signals to interrupt getdents copying Documentation: fix typo in root= kernel parameter description include/cgroup: separate {get,put}_cgroup_ns no-op case kernel/nsproxy: remove unnecessary guards fs: use writeback_iter directly in mpage_writepages fs: remove useless plus one in super_cache_scan() fs: add S_ANON_INODE fs: remove uselib() system call device_cgroup: avoid access to ->i_rdev in the common case in devcgroup_inode_permission() fs/fs_parse: Remove unused and problematic validate_constant_table() fs: touch up predicts in inode_permission() ...

readdir: supply dir_context.count as readdir buffer size hint

2025-05-15T09:26:05+00:00

This is a preparation for large readdir buffers in fuse. Simply setting the fuse buffer size to the userspace buffer size should work, the record sizes are similar (fuse's is slightly larger than libc's, so no overflow should ever happen). Signed-off-by: Miklos Szeredi Signed-off-by: Jaco Kroon Link: https://lore.kernel.org/20250513151012.1476536-1-mszeredi@redhat.com Signed-off-by: Christian Brauner

VFS: improve interface for lookup_one functions

2025-04-07T07:25:32+00:00

The family of functions: lookup_one() lookup_one_unlocked() lookup_one_positive_unlocked() appear designed to be used by external clients of the filesystem rather than by filesystems acting on themselves as the lookup_one_len family are used. They are used by: btrfs/ioctl - which is a user-space interface rather than an internal activity exportfs - i.e. from nfsd or the open_by_handle_at interface overlayfs - at access the underlying filesystems smb/server - for file service They should be used by nfsd (more than just the exportfs path) and cachefs but aren't. It would help if the documentation didn't claim they should "not be called by generic code". Also the path component name is passed as "name" and "len" which are (confusingly?) separate by the "base". In some cases the len in simply "strlen" and so passing a qstr using QSTR() would make the calling clearer. Other callers do pass separate name and len which are stored in a struct. Sometimes these are already stored in a qstr, other times it easily could be. So this patch changes these three functions to receive a 'struct qstr *', and improves the documentation. QSTR_LEN() is added to make it easy to pass a QSTR containing a known len. [brauner@kernel.org: take a struct qstr pointer] Signed-off-by: NeilBrown Link: https://lore.kernel.org/r/20250319031545.2999807-2-neil@brown.name Signed-off-by: Christian Brauner

exportfs: add module description

2025-03-25T14:57:58+00:00

Every loadable module should have a description, to avoid a warning such as: WARNING: modpost: missing MODULE_DESCRIPTION() in fs/exportfs/exportfs.o Signed-off-by: Arnd Bergmann Link: https://lore.kernel.org/r/20250324173242.1501003-1-arnd@kernel.org Signed-off-by: Christian Brauner

exportfs: remove locking around ->get_parent() call.

2025-03-14T10:39:59+00:00

The locking around the ->get_parent() call brings no value. We are locking a child which is only used to find an inode and thence the parent inode number. All further activity involves the parent inode which may have several children so locking one child cannot protect the parent in any useful way. The filesystem must already ensure that only one 'struct inode' exists for a given inode, and will call d_obtain_alias() which contains the required locking to ensure only one dentry will be attached to that inode. So remove the unnecessary locking. Signed-off-by: NeilBrown Link: https://lore.kernel.org/r/174190497326.9342.9313518146512158587@noble.neil.brown.name Signed-off-by: Christian Brauner