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![Christian Brauner](/assets/img/avatar_default.png)
Convert to struct mnt_idmap.
Last cycle we merged the necessary infrastructure in
256c8aed2b
("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.
Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.
Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
235 lines
5.8 KiB
C
235 lines
5.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* linux/fs/sysv/ialloc.c
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*
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* minix/bitmap.c
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* Copyright (C) 1991, 1992 Linus Torvalds
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*
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* ext/freelists.c
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* Copyright (C) 1992 Remy Card (card@masi.ibp.fr)
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*
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* xenix/alloc.c
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* Copyright (C) 1992 Doug Evans
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*
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* coh/alloc.c
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* Copyright (C) 1993 Pascal Haible, Bruno Haible
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*
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* sysv/ialloc.c
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* Copyright (C) 1993 Bruno Haible
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*
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* This file contains code for allocating/freeing inodes.
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*/
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#include <linux/kernel.h>
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#include <linux/stddef.h>
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#include <linux/sched.h>
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#include <linux/stat.h>
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#include <linux/string.h>
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#include <linux/buffer_head.h>
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#include <linux/writeback.h>
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#include "sysv.h"
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/* We don't trust the value of
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sb->sv_sbd2->s_tinode = *sb->sv_sb_total_free_inodes
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but we nevertheless keep it up to date. */
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/* An inode on disk is considered free if both i_mode == 0 and i_nlink == 0. */
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/* return &sb->sv_sb_fic_inodes[i] = &sbd->s_inode[i]; */
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static inline sysv_ino_t *
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sv_sb_fic_inode(struct super_block * sb, unsigned int i)
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{
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struct sysv_sb_info *sbi = SYSV_SB(sb);
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if (sbi->s_bh1 == sbi->s_bh2)
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return &sbi->s_sb_fic_inodes[i];
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else {
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/* 512 byte Xenix FS */
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unsigned int offset = offsetof(struct xenix_super_block, s_inode[i]);
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if (offset < 512)
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return (sysv_ino_t*)(sbi->s_sbd1 + offset);
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else
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return (sysv_ino_t*)(sbi->s_sbd2 + offset);
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}
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}
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struct sysv_inode *
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sysv_raw_inode(struct super_block *sb, unsigned ino, struct buffer_head **bh)
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{
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struct sysv_sb_info *sbi = SYSV_SB(sb);
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struct sysv_inode *res;
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int block = sbi->s_firstinodezone + sbi->s_block_base;
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block += (ino-1) >> sbi->s_inodes_per_block_bits;
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*bh = sb_bread(sb, block);
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if (!*bh)
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return NULL;
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res = (struct sysv_inode *)(*bh)->b_data;
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return res + ((ino-1) & sbi->s_inodes_per_block_1);
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}
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static int refill_free_cache(struct super_block *sb)
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{
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struct sysv_sb_info *sbi = SYSV_SB(sb);
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struct buffer_head * bh;
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struct sysv_inode * raw_inode;
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int i = 0, ino;
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ino = SYSV_ROOT_INO+1;
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raw_inode = sysv_raw_inode(sb, ino, &bh);
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if (!raw_inode)
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goto out;
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while (ino <= sbi->s_ninodes) {
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if (raw_inode->i_mode == 0 && raw_inode->i_nlink == 0) {
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*sv_sb_fic_inode(sb,i++) = cpu_to_fs16(SYSV_SB(sb), ino);
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if (i == sbi->s_fic_size)
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break;
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}
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if ((ino++ & sbi->s_inodes_per_block_1) == 0) {
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brelse(bh);
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raw_inode = sysv_raw_inode(sb, ino, &bh);
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if (!raw_inode)
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goto out;
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} else
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raw_inode++;
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}
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brelse(bh);
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out:
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return i;
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}
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void sysv_free_inode(struct inode * inode)
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{
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struct super_block *sb = inode->i_sb;
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struct sysv_sb_info *sbi = SYSV_SB(sb);
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unsigned int ino;
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struct buffer_head * bh;
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struct sysv_inode * raw_inode;
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unsigned count;
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sb = inode->i_sb;
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ino = inode->i_ino;
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if (ino <= SYSV_ROOT_INO || ino > sbi->s_ninodes) {
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printk("sysv_free_inode: inode 0,1,2 or nonexistent inode\n");
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return;
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}
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raw_inode = sysv_raw_inode(sb, ino, &bh);
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if (!raw_inode) {
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printk("sysv_free_inode: unable to read inode block on device "
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"%s\n", inode->i_sb->s_id);
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return;
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}
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mutex_lock(&sbi->s_lock);
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count = fs16_to_cpu(sbi, *sbi->s_sb_fic_count);
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if (count < sbi->s_fic_size) {
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*sv_sb_fic_inode(sb,count++) = cpu_to_fs16(sbi, ino);
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*sbi->s_sb_fic_count = cpu_to_fs16(sbi, count);
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}
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fs16_add(sbi, sbi->s_sb_total_free_inodes, 1);
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dirty_sb(sb);
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memset(raw_inode, 0, sizeof(struct sysv_inode));
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mark_buffer_dirty(bh);
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mutex_unlock(&sbi->s_lock);
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brelse(bh);
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}
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struct inode * sysv_new_inode(const struct inode * dir, umode_t mode)
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{
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struct super_block *sb = dir->i_sb;
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struct sysv_sb_info *sbi = SYSV_SB(sb);
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struct inode *inode;
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sysv_ino_t ino;
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unsigned count;
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struct writeback_control wbc = {
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.sync_mode = WB_SYNC_NONE
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};
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inode = new_inode(sb);
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if (!inode)
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return ERR_PTR(-ENOMEM);
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mutex_lock(&sbi->s_lock);
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count = fs16_to_cpu(sbi, *sbi->s_sb_fic_count);
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if (count == 0 || (*sv_sb_fic_inode(sb,count-1) == 0)) {
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count = refill_free_cache(sb);
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if (count == 0) {
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iput(inode);
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mutex_unlock(&sbi->s_lock);
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return ERR_PTR(-ENOSPC);
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}
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}
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/* Now count > 0. */
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ino = *sv_sb_fic_inode(sb,--count);
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*sbi->s_sb_fic_count = cpu_to_fs16(sbi, count);
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fs16_add(sbi, sbi->s_sb_total_free_inodes, -1);
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dirty_sb(sb);
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inode_init_owner(&nop_mnt_idmap, inode, dir, mode);
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inode->i_ino = fs16_to_cpu(sbi, ino);
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inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
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inode->i_blocks = 0;
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memset(SYSV_I(inode)->i_data, 0, sizeof(SYSV_I(inode)->i_data));
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SYSV_I(inode)->i_dir_start_lookup = 0;
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insert_inode_hash(inode);
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mark_inode_dirty(inode);
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sysv_write_inode(inode, &wbc); /* ensure inode not allocated again */
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mark_inode_dirty(inode); /* cleared by sysv_write_inode() */
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/* That's it. */
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mutex_unlock(&sbi->s_lock);
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return inode;
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}
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unsigned long sysv_count_free_inodes(struct super_block * sb)
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{
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struct sysv_sb_info *sbi = SYSV_SB(sb);
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struct buffer_head * bh;
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struct sysv_inode * raw_inode;
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int ino, count, sb_count;
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mutex_lock(&sbi->s_lock);
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sb_count = fs16_to_cpu(sbi, *sbi->s_sb_total_free_inodes);
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if (0)
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goto trust_sb;
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/* this causes a lot of disk traffic ... */
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count = 0;
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ino = SYSV_ROOT_INO+1;
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raw_inode = sysv_raw_inode(sb, ino, &bh);
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if (!raw_inode)
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goto Eio;
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while (ino <= sbi->s_ninodes) {
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if (raw_inode->i_mode == 0 && raw_inode->i_nlink == 0)
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count++;
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if ((ino++ & sbi->s_inodes_per_block_1) == 0) {
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brelse(bh);
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raw_inode = sysv_raw_inode(sb, ino, &bh);
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if (!raw_inode)
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goto Eio;
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} else
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raw_inode++;
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}
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brelse(bh);
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if (count != sb_count)
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goto Einval;
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out:
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mutex_unlock(&sbi->s_lock);
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return count;
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Einval:
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printk("sysv_count_free_inodes: "
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"free inode count was %d, correcting to %d\n",
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sb_count, count);
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if (!sb_rdonly(sb)) {
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*sbi->s_sb_total_free_inodes = cpu_to_fs16(SYSV_SB(sb), count);
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dirty_sb(sb);
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}
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goto out;
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Eio:
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printk("sysv_count_free_inodes: unable to read inode table\n");
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trust_sb:
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count = sb_count;
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goto out;
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}
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