225 lines
7.5 KiB
C
225 lines
7.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/* Filesystem superblock creation and reconfiguration context.
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*
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* Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#ifndef _LINUX_FS_CONTEXT_H
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#define _LINUX_FS_CONTEXT_H
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#include <linux/kernel.h>
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#include <linux/refcount.h>
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#include <linux/errno.h>
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#include <linux/security.h>
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#include <linux/mutex.h>
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struct cred;
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struct dentry;
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struct file_operations;
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struct file_system_type;
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struct mnt_namespace;
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struct net;
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struct pid_namespace;
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struct super_block;
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struct user_namespace;
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struct vfsmount;
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struct path;
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enum fs_context_purpose {
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FS_CONTEXT_FOR_MOUNT, /* New superblock for explicit mount */
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FS_CONTEXT_FOR_SUBMOUNT, /* New superblock for automatic submount */
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FS_CONTEXT_FOR_RECONFIGURE, /* Superblock reconfiguration (remount) */
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};
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/*
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* Userspace usage phase for fsopen/fspick.
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*/
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enum fs_context_phase {
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FS_CONTEXT_CREATE_PARAMS, /* Loading params for sb creation */
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FS_CONTEXT_CREATING, /* A superblock is being created */
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FS_CONTEXT_AWAITING_MOUNT, /* Superblock created, awaiting fsmount() */
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FS_CONTEXT_AWAITING_RECONF, /* Awaiting initialisation for reconfiguration */
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FS_CONTEXT_RECONF_PARAMS, /* Loading params for reconfiguration */
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FS_CONTEXT_RECONFIGURING, /* Reconfiguring the superblock */
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FS_CONTEXT_FAILED, /* Failed to correctly transition a context */
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};
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/*
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* Type of parameter value.
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*/
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enum fs_value_type {
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fs_value_is_undefined,
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fs_value_is_flag, /* Value not given a value */
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fs_value_is_string, /* Value is a string */
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fs_value_is_blob, /* Value is a binary blob */
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fs_value_is_filename, /* Value is a filename* + dirfd */
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fs_value_is_filename_empty, /* Value is a filename* + dirfd + AT_EMPTY_PATH */
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fs_value_is_file, /* Value is a file* */
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};
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/*
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* Configuration parameter.
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*/
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struct fs_parameter {
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const char *key; /* Parameter name */
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enum fs_value_type type:8; /* The type of value here */
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union {
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char *string;
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void *blob;
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struct filename *name;
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struct file *file;
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};
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size_t size;
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int dirfd;
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};
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/*
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* Filesystem context for holding the parameters used in the creation or
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* reconfiguration of a superblock.
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*
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* Superblock creation fills in ->root whereas reconfiguration begins with this
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* already set.
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*
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* See Documentation/filesystems/mount_api.txt
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*/
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struct fs_context {
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const struct fs_context_operations *ops;
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struct mutex uapi_mutex; /* Userspace access mutex */
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struct file_system_type *fs_type;
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void *fs_private; /* The filesystem's context */
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void *sget_key;
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struct dentry *root; /* The root and superblock */
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struct user_namespace *user_ns; /* The user namespace for this mount */
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struct net *net_ns; /* The network namespace for this mount */
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const struct cred *cred; /* The mounter's credentials */
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struct fc_log *log; /* Logging buffer */
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const char *source; /* The source name (eg. dev path) */
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void *security; /* Linux S&M options */
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void *s_fs_info; /* Proposed s_fs_info */
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unsigned int sb_flags; /* Proposed superblock flags (SB_*) */
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unsigned int sb_flags_mask; /* Superblock flags that were changed */
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unsigned int s_iflags; /* OR'd with sb->s_iflags */
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unsigned int lsm_flags; /* Information flags from the fs to the LSM */
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enum fs_context_purpose purpose:8;
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enum fs_context_phase phase:8; /* The phase the context is in */
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bool need_free:1; /* Need to call ops->free() */
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bool global:1; /* Goes into &init_user_ns */
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};
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struct fs_context_operations {
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void (*free)(struct fs_context *fc);
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int (*dup)(struct fs_context *fc, struct fs_context *src_fc);
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int (*parse_param)(struct fs_context *fc, struct fs_parameter *param);
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int (*parse_monolithic)(struct fs_context *fc, void *data);
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int (*get_tree)(struct fs_context *fc);
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int (*reconfigure)(struct fs_context *fc);
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};
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/*
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* fs_context manipulation functions.
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*/
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extern struct fs_context *fs_context_for_mount(struct file_system_type *fs_type,
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unsigned int sb_flags);
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extern struct fs_context *fs_context_for_reconfigure(struct dentry *dentry,
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unsigned int sb_flags,
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unsigned int sb_flags_mask);
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extern struct fs_context *fs_context_for_submount(struct file_system_type *fs_type,
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struct dentry *reference);
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extern struct fs_context *vfs_dup_fs_context(struct fs_context *fc);
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extern int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param);
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extern int vfs_parse_fs_string(struct fs_context *fc, const char *key,
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const char *value, size_t v_size);
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extern int generic_parse_monolithic(struct fs_context *fc, void *data);
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extern int vfs_get_tree(struct fs_context *fc);
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extern void put_fs_context(struct fs_context *fc);
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/*
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* sget() wrappers to be called from the ->get_tree() op.
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*/
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enum vfs_get_super_keying {
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vfs_get_single_super, /* Only one such superblock may exist */
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vfs_get_keyed_super, /* Superblocks with different s_fs_info keys may exist */
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vfs_get_independent_super, /* Multiple independent superblocks may exist */
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};
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extern int vfs_get_super(struct fs_context *fc,
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enum vfs_get_super_keying keying,
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int (*fill_super)(struct super_block *sb,
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struct fs_context *fc));
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extern int get_tree_nodev(struct fs_context *fc,
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int (*fill_super)(struct super_block *sb,
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struct fs_context *fc));
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extern int get_tree_single(struct fs_context *fc,
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int (*fill_super)(struct super_block *sb,
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struct fs_context *fc));
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extern int get_tree_keyed(struct fs_context *fc,
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int (*fill_super)(struct super_block *sb,
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struct fs_context *fc),
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void *key);
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extern int get_tree_bdev(struct fs_context *fc,
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int (*fill_super)(struct super_block *sb,
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struct fs_context *fc));
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extern const struct file_operations fscontext_fops;
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/*
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* Mount error, warning and informational message logging. This structure is
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* shareable between a mount and a subordinate mount.
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*/
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struct fc_log {
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refcount_t usage;
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u8 head; /* Insertion index in buffer[] */
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u8 tail; /* Removal index in buffer[] */
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u8 need_free; /* Mask of kfree'able items in buffer[] */
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struct module *owner; /* Owner module for strings that don't then need freeing */
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char *buffer[8];
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};
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extern __attribute__((format(printf, 2, 3)))
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void logfc(struct fs_context *fc, const char *fmt, ...);
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/**
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* infof - Store supplementary informational message
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* @fc: The context in which to log the informational message
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* @fmt: The format string
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*
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* Store the supplementary informational message for the process if the process
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* has enabled the facility.
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*/
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#define infof(fc, fmt, ...) ({ logfc(fc, "i "fmt, ## __VA_ARGS__); })
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/**
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* warnf - Store supplementary warning message
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* @fc: The context in which to log the error message
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* @fmt: The format string
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*
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* Store the supplementary warning message for the process if the process has
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* enabled the facility.
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*/
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#define warnf(fc, fmt, ...) ({ logfc(fc, "w "fmt, ## __VA_ARGS__); })
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/**
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* errorf - Store supplementary error message
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* @fc: The context in which to log the error message
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* @fmt: The format string
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*
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* Store the supplementary error message for the process if the process has
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* enabled the facility.
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*/
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#define errorf(fc, fmt, ...) ({ logfc(fc, "e "fmt, ## __VA_ARGS__); })
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/**
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* invalf - Store supplementary invalid argument error message
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* @fc: The context in which to log the error message
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* @fmt: The format string
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*
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* Store the supplementary error message for the process if the process has
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* enabled the facility and return -EINVAL.
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*/
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#define invalf(fc, fmt, ...) ({ errorf(fc, fmt, ## __VA_ARGS__); -EINVAL; })
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#endif /* _LINUX_FS_CONTEXT_H */
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