10c9700f3e
There are a number of msdosfs improvements in NetBSD that may be worth bringing over, and this reduces noise in the comparison. Differential Revision: https://reviews.freebsd.org/D1466 Reviewed by: kib Sponsored by: The FreeBSD Foundation
153 lines
5.1 KiB
C
153 lines
5.1 KiB
C
/*-
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* Copyright (c) 2003-2004 Tim J. Robbins.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* Compress 64-bit file numbers into temporary, unique 32-bit file numbers.
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* This is needed because the algorithm we use to calculate these numbers
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* generates 64-bit quantities, but struct dirent's d_fileno member and
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* struct vnodeattr's va_fileid member only have space for 32 bits.
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*
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* 32-bit file numbers are generated sequentially, and stored in a
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* red-black tree, indexed on 64-bit file number. The mappings do not
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* persist across reboots (or unmounts); anything that relies on this
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* (e.g. NFS) will not work correctly. This scheme consumes 32 bytes
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* of kernel memory per file (on i386), and it may be possible for a user
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* to cause a panic by creating millions of tiny files.
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*
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* As an optimization, we split the file number space between statically
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* allocated and dynamically allocated. File numbers less than
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* FILENO_FIRST_DYN are left unchanged and do not have any tree nodes
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* allocated to them.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/mount.h>
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#include <fs/msdosfs/bpb.h>
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#include <fs/msdosfs/direntry.h>
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#include <fs/msdosfs/msdosfsmount.h>
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static MALLOC_DEFINE(M_MSDOSFSFILENO, "msdosfs_fileno", "MSDOSFS fileno mapping node");
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RB_PROTOTYPE(msdosfs_filenotree, msdosfs_fileno, mf_tree,
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msdosfs_fileno_compare)
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static int msdosfs_fileno_compare(struct msdosfs_fileno *,
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struct msdosfs_fileno *);
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#define FILENO_FIRST_DYN 0xf0000000
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/* Initialize file number mapping structures. */
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void
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msdosfs_fileno_init(struct mount *mp)
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{
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struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
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RB_INIT(&pmp->pm_filenos);
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pmp->pm_nfileno = FILENO_FIRST_DYN;
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if (pmp->pm_HugeSectors > 0xffffffff /
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(pmp->pm_BytesPerSec / sizeof(struct direntry)) + 1)
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pmp->pm_flags |= MSDOSFS_LARGEFS;
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}
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/* Free 32-bit file number generation structures. */
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void
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msdosfs_fileno_free(struct mount *mp)
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{
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struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
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struct msdosfs_fileno *mf, *next;
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for (mf = RB_MIN(msdosfs_filenotree, &pmp->pm_filenos); mf != NULL;
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mf = next) {
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next = RB_NEXT(msdosfs_filenotree, &pmp->pm_filenos, mf);
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RB_REMOVE(msdosfs_filenotree, &pmp->pm_filenos, mf);
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free(mf, M_MSDOSFSFILENO);
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}
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}
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/* Map a 64-bit file number into a 32-bit one. */
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uint32_t
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msdosfs_fileno_map(struct mount *mp, uint64_t fileno)
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{
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struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
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struct msdosfs_fileno key, *mf, *tmf;
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uint32_t mapped;
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if ((pmp->pm_flags & MSDOSFS_LARGEFS) == 0) {
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KASSERT((uint32_t)fileno == fileno,
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("fileno >32 bits but not a large fs?"));
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return ((uint32_t)fileno);
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}
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if (fileno < FILENO_FIRST_DYN)
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return ((uint32_t)fileno);
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MSDOSFS_LOCK_MP(pmp);
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key.mf_fileno64 = fileno;
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mf = RB_FIND(msdosfs_filenotree, &pmp->pm_filenos, &key);
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if (mf != NULL) {
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mapped = mf->mf_fileno32;
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MSDOSFS_UNLOCK_MP(pmp);
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return (mapped);
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}
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if (pmp->pm_nfileno < FILENO_FIRST_DYN)
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panic("msdosfs_fileno_map: wraparound");
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MSDOSFS_UNLOCK_MP(pmp);
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mf = malloc(sizeof(*mf), M_MSDOSFSFILENO, M_WAITOK);
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MSDOSFS_LOCK_MP(pmp);
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tmf = RB_FIND(msdosfs_filenotree, &pmp->pm_filenos, &key);
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if (tmf != NULL) {
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mapped = tmf->mf_fileno32;
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MSDOSFS_UNLOCK_MP(pmp);
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free(mf, M_MSDOSFSFILENO);
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return (mapped);
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}
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mf->mf_fileno64 = fileno;
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mapped = mf->mf_fileno32 = pmp->pm_nfileno++;
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RB_INSERT(msdosfs_filenotree, &pmp->pm_filenos, mf);
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MSDOSFS_UNLOCK_MP(pmp);
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return (mapped);
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}
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/* Compare by 64-bit file number. */
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static int
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msdosfs_fileno_compare(struct msdosfs_fileno *fa, struct msdosfs_fileno *fb)
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{
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if (fa->mf_fileno64 > fb->mf_fileno64)
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return (1);
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else if (fa->mf_fileno64 < fb->mf_fileno64)
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return (-1);
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return (0);
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}
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RB_GENERATE(msdosfs_filenotree, msdosfs_fileno, mf_tree,
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msdosfs_fileno_compare)
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