diff options
Diffstat (limited to 'sys/contrib/openzfs/module/os/linux/zfs/zpl_super.c')
| -rw-r--r-- | sys/contrib/openzfs/module/os/linux/zfs/zpl_super.c | 85 |
1 files changed, 81 insertions, 4 deletions
diff --git a/sys/contrib/openzfs/module/os/linux/zfs/zpl_super.c b/sys/contrib/openzfs/module/os/linux/zfs/zpl_super.c index 53819628627d..444948d03cb3 100644 --- a/sys/contrib/openzfs/module/os/linux/zfs/zpl_super.c +++ b/sys/contrib/openzfs/module/os/linux/zfs/zpl_super.c @@ -22,6 +22,7 @@ /* * Copyright (c) 2011, Lawrence Livermore National Security, LLC. * Copyright (c) 2023, Datto Inc. All rights reserved. + * Copyright (c) 2025, Klara, Inc. */ @@ -33,6 +34,20 @@ #include <linux/iversion.h> #include <linux/version.h> +/* + * What to do when the last reference to an inode is released. If 0, the kernel + * will cache it on the superblock. If 1, the inode will be freed immediately. + * See zpl_drop_inode(). + */ +int zfs_delete_inode = 0; + +/* + * What to do when the last reference to a dentry is released. If 0, the kernel + * will cache it until the entry (file) is destroyed. If 1, the dentry will be + * marked for cleanup, at which time its inode reference will be released. See + * zpl_dentry_delete(). + */ +int zfs_delete_dentry = 0; static struct inode * zpl_inode_alloc(struct super_block *sb) @@ -77,11 +92,36 @@ zpl_dirty_inode(struct inode *ip, int flags) } /* - * When ->drop_inode() is called its return value indicates if the - * inode should be evicted from the inode cache. If the inode is - * unhashed and has no links the default policy is to evict it - * immediately. + * ->drop_inode() is called when the last reference to an inode is released. + * Its return value indicates if the inode should be destroyed immediately, or + * cached on the superblock structure. + * + * By default (zfs_delete_inode=0), we call generic_drop_inode(), which returns + * "destroy immediately" if the inode is unhashed and has no links (roughly: no + * longer exists on disk). On datasets with millions of rarely-accessed files, + * this can cause a large amount of memory to be "pinned" by cached inodes, + * which in turn pin their associated dnodes and dbufs, until the kernel starts + * reporting memory pressure and requests OpenZFS release some memory (see + * zfs_prune()). + * + * When set to 1, we call generic_delete_node(), which always returns "destroy + * immediately", resulting in inodes being destroyed immediately, releasing + * their associated dnodes and dbufs to the dbuf cached and the ARC to be + * evicted as normal. * + * Note that the "last reference" doesn't always mean the last _userspace_ + * reference; the dentry cache also holds a reference, so "busy" inodes will + * still be kept alive that way (subject to dcache tuning). + */ +static int +zpl_drop_inode(struct inode *ip) +{ + if (zfs_delete_inode) + return (generic_delete_inode(ip)); + return (generic_drop_inode(ip)); +} + +/* * The ->evict_inode() callback must minimally truncate the inode pages, * and call clear_inode(). For 2.6.35 and later kernels this will * simply update the inode state, with the sync occurring before the @@ -470,6 +510,7 @@ const struct super_operations zpl_super_operations = { .destroy_inode = zpl_inode_destroy, .dirty_inode = zpl_dirty_inode, .write_inode = NULL, + .drop_inode = zpl_drop_inode, .evict_inode = zpl_evict_inode, .put_super = zpl_put_super, .sync_fs = zpl_sync_fs, @@ -480,6 +521,35 @@ const struct super_operations zpl_super_operations = { .show_stats = NULL, }; +/* + * ->d_delete() is called when the last reference to a dentry is released. Its + * return value indicates if the dentry should be destroyed immediately, or + * retained in the dentry cache. + * + * By default (zfs_delete_dentry=0) the kernel will always cache unused + * entries. Each dentry holds an inode reference, so cached dentries can hold + * the final inode reference indefinitely, leading to the inode and its related + * data being pinned (see zpl_drop_inode()). + * + * When set to 1, we signal that the dentry should be destroyed immediately and + * never cached. This reduces memory usage, at the cost of higher overheads to + * lookup a file, as the inode and its underlying data (dnode/dbuf) need to be + * reloaded and reinflated. + * + * Note that userspace does not have direct control over dentry references and + * reclaim; rather, this is part of the kernel's caching and reclaim subsystems + * (eg vm.vfs_cache_pressure). + */ +static int +zpl_dentry_delete(const struct dentry *dentry) +{ + return (zfs_delete_dentry ? 1 : 0); +} + +const struct dentry_operations zpl_dentry_operations = { + .d_delete = zpl_dentry_delete, +}; + struct file_system_type zpl_fs_type = { .owner = THIS_MODULE, .name = ZFS_DRIVER, @@ -491,3 +561,10 @@ struct file_system_type zpl_fs_type = { .mount = zpl_mount, .kill_sb = zpl_kill_sb, }; + +ZFS_MODULE_PARAM(zfs, zfs_, delete_inode, INT, ZMOD_RW, + "Delete inodes as soon as the last reference is released."); + +ZFS_MODULE_PARAM(zfs, zfs_, delete_dentry, INT, ZMOD_RW, + "Delete dentries from dentry cache as soon as the last reference is " + "released."); |