2 * Copyright (c) 2003-2004 Tim J. Robbins.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * Compress 64-bit file numbers into temporary, unique 32-bit file numbers.
28 * This is needed because the algorithm we use to calculate these numbers
29 * generates 64-bit quantities, but struct dirent's d_fileno member and
30 * struct vnodeattr's va_fileid member only have space for 32 bits.
32 * 32-bit file numbers are generated sequentially, and stored in a
33 * red-black tree, indexed on 64-bit file number. The mappings do not
34 * persist across reboots (or unmounts); anything that relies on this
35 * (e.g. NFS) will not work correctly. This scheme consumes 32 bytes
36 * of kernel memory per file (on i386), and it may be possible for a user
37 * to cause a panic by creating millions of tiny files.
39 * As an optimization, we split the file number space between statically
40 * allocated and dynamically allocated. File numbers less than
41 * FILENO_FIRST_DYN are left unchanged and do not have any tree nodes
45 #include <sys/cdefs.h>
46 __FBSDID("$FreeBSD$");
48 #include <sys/param.h>
49 #include <sys/systm.h>
50 #include <sys/kernel.h>
52 #include <sys/malloc.h>
53 #include <sys/mount.h>
55 #include <fs/msdosfs/bpb.h>
56 #include <fs/msdosfs/direntry.h>
57 #include <fs/msdosfs/msdosfsmount.h>
59 static MALLOC_DEFINE(M_MSDOSFSFILENO, "msdosfs_fileno", "MSDOSFS fileno mapping node");
61 RB_PROTOTYPE(msdosfs_filenotree, msdosfs_fileno, mf_tree,
62 msdosfs_fileno_compare)
64 static int msdosfs_fileno_compare(struct msdosfs_fileno *,
65 struct msdosfs_fileno *);
67 #define FILENO_FIRST_DYN 0xf0000000
69 /* Initialize file number mapping structures. */
71 msdosfs_fileno_init(mp)
74 struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
76 RB_INIT(&pmp->pm_filenos);
77 pmp->pm_nfileno = FILENO_FIRST_DYN;
78 if (pmp->pm_HugeSectors > 0xffffffff /
79 (pmp->pm_BytesPerSec / sizeof(struct direntry)) + 1)
80 pmp->pm_flags |= MSDOSFS_LARGEFS;
83 /* Free 32-bit file number generation structures. */
85 msdosfs_fileno_free(mp)
88 struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
89 struct msdosfs_fileno *mf, *next;
91 for (mf = RB_MIN(msdosfs_filenotree, &pmp->pm_filenos); mf != NULL;
93 next = RB_NEXT(msdosfs_filenotree, &pmp->pm_filenos, mf);
94 RB_REMOVE(msdosfs_filenotree, &pmp->pm_filenos, mf);
95 free(mf, M_MSDOSFSFILENO);
99 /* Map a 64-bit file number into a 32-bit one. */
101 msdosfs_fileno_map(mp, fileno)
105 struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
106 struct msdosfs_fileno key, *mf, *tmf;
109 if ((pmp->pm_flags & MSDOSFS_LARGEFS) == 0) {
110 KASSERT((uint32_t)fileno == fileno,
111 ("fileno >32 bits but not a large fs?"));
112 return ((uint32_t)fileno);
114 if (fileno < FILENO_FIRST_DYN)
115 return ((uint32_t)fileno);
116 MSDOSFS_LOCK_MP(pmp);
117 key.mf_fileno64 = fileno;
118 mf = RB_FIND(msdosfs_filenotree, &pmp->pm_filenos, &key);
120 mapped = mf->mf_fileno32;
121 MSDOSFS_UNLOCK_MP(pmp);
124 if (pmp->pm_nfileno < FILENO_FIRST_DYN)
125 panic("msdosfs_fileno_map: wraparound");
126 MSDOSFS_UNLOCK_MP(pmp);
127 mf = malloc(sizeof(*mf), M_MSDOSFSFILENO, M_WAITOK);
128 MSDOSFS_LOCK_MP(pmp);
129 tmf = RB_FIND(msdosfs_filenotree, &pmp->pm_filenos, &key);
131 mapped = tmf->mf_fileno32;
132 MSDOSFS_UNLOCK_MP(pmp);
133 free(mf, M_MSDOSFSFILENO);
136 mf->mf_fileno64 = fileno;
137 mapped = mf->mf_fileno32 = pmp->pm_nfileno++;
138 RB_INSERT(msdosfs_filenotree, &pmp->pm_filenos, mf);
139 MSDOSFS_UNLOCK_MP(pmp);
143 /* Compare by 64-bit file number. */
145 msdosfs_fileno_compare(fa, fb)
146 struct msdosfs_fileno *fa, *fb;
149 if (fa->mf_fileno64 > fb->mf_fileno64)
151 else if (fa->mf_fileno64 < fb->mf_fileno64)
156 RB_GENERATE(msdosfs_filenotree, msdosfs_fileno, mf_tree,
157 msdosfs_fileno_compare)