fs/ext2/file.c

   1 /*
   2  *  linux/fs/ext2/file.c
   3  *
   4  * Copyright (C) 1992, 1993, 1994, 1995
   5  * Remy Card (card@masi.ibp.fr)
   6  * Laboratoire MASI - Institut Blaise Pascal
   7  * Universite Pierre et Marie Curie (Paris VI)
   8  *
   9  *  from
  10  *
  11  *  linux/fs/minix/file.c
  12  *
  13  *  Copyright (C) 1991, 1992  Linus Torvalds
  14  *
  15  *  ext2 fs regular file handling primitives
  16  *
  17  *  64-bit file support on 64-bit platforms by Jakub Jelinek
  18  *      (jj@sunsite.ms.mff.cuni.cz)
  19  */
  20
  21 #include <asm/uaccess.h>
  22 #include <asm/system.h>
  23
  24 #include <linux/errno.h>
  25 #include <linux/fs.h>
  26 #include <linux/ext2_fs.h>
  27 #include <linux/fcntl.h>
  28 #include <linux/sched.h>
  29 #include <linux/stat.h>
  30 #include <linux/locks.h>
  31 #include <linux/mm.h>
  32 #include <linux/pagemap.h>
  33 #include <linux/smp_lock.h>
  34
  35 #define NBUF    32
  36
  37 #define MIN(a,b) (((a)<(b))?(a):(b))
  38 #define MAX(a,b) (((a)>(b))?(a):(b))
  39
  40 static int ext2_writepage (struct file * file, struct page * page);
  41 static long long ext2_file_lseek(struct file *, long long, int);
  42 #if BITS_PER_LONG < 64
  43 static int ext2_open_file (struct inode *, struct file *);
  44
  45 #else
  46
  47 #define EXT2_MAX_SIZE(bits)                                                     \
  48         (((EXT2_NDIR_BLOCKS + (1LL << (bits - 2)) +                             \
  49            (1LL << (bits - 2)) * (1LL << (bits - 2)) +                          \
  50            (1LL << (bits - 2)) * (1LL << (bits - 2)) * (1LL << (bits - 2))) *   \
  51           (1LL << bits)) - 1)
  52
  53 static long long ext2_max_sizes[] = {
  54 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  55 EXT2_MAX_SIZE(10), EXT2_MAX_SIZE(11), EXT2_MAX_SIZE(12), EXT2_MAX_SIZE(13)
  56 };
  57
  58 #endif
  59
  60
  61 /*
  62  * Make sure the offset never goes beyond the 32-bit mark..
  63  */
  64 static long long ext2_file_lseek(
  65         struct file *file,
  66         long long offset,
  67         int origin)
  68 {
  69         struct inode *inode = file->f_dentry->d_inode;
  70
  71         switch (origin) {
  72                 case 2:
  73                         offset += inode->i_size;
  74                         break;
  75                 case 1:
  76                         offset += file->f_pos;
  77         }
  78         if (((unsigned long long) offset >> 32) != 0) {
  79 #if BITS_PER_LONG < 64
  80                 return -EINVAL;
  81 #else
  82                 if (offset > ext2_max_sizes[EXT2_BLOCK_SIZE_BITS(inode->i_sb)])
  83                         return -EINVAL;
  84 #endif
  85         }
  86         if (offset != file->f_pos) {
  87                 file->f_pos = offset;
  88                 file->f_reada = 0;
  89                 file->f_version = ++event;
  90         }
  91         return offset;
  92 }
  93
  94 static inline void remove_suid(struct inode *inode)
  95 {
  96         unsigned int mode;
  97
  98         /* set S_IGID if S_IXGRP is set, and always set S_ISUID */
  99         mode = (inode->i_mode & S_IXGRP)*(S_ISGID/S_IXGRP) | S_ISUID;
 100
 101         /* was any of the uid bits set? */
 102         mode &= inode->i_mode;
 103         if (mode && !capable(CAP_FSETID)) {
 104                 inode->i_mode &= ~mode;
 105                 mark_inode_dirty(inode);
 106         }
 107 }
 108
 109 static int ext2_writepage (struct file * file, struct page * page)
 110 {
 111         return block_write_full_page(file, page, ext2_getblk_block);
 112 }
 113
 114 static long ext2_write_one_page (struct file *file, struct page *page, unsigned long offset, unsigned long bytes, const char * buf)
 115 {
 116         return block_write_one_page(file, page, offset, bytes, buf, ext2_getblk_block);
 117 }
 118
 119 /*
 120  * Write to a file (through the page cache).
 121  */
 122 static ssize_t
 123 ext2_file_write(struct file *file, const char *buf, size_t count, loff_t *ppos)
 124 {
 125         return generic_file_write(file, buf, count, ppos, ext2_write_one_page);
 126 }
 127
 128 /*
 129  * Called when an inode is released. Note that this is different
 130  * from ext2_file_open: open gets called at every open, but release
 131  * gets called only when /all/ the files are closed.
 132  */
 133 static int ext2_release_file (struct inode * inode, struct file * filp)
 134 {
 135         if (filp->f_mode & FMODE_WRITE)
 136                 ext2_discard_prealloc (inode);
 137         return 0;
 138 }
 139
 140 #if BITS_PER_LONG < 64
 141 /*
 142  * Called when an inode is about to be open.
 143  * We use this to disallow opening RW large files on 32bit systems.
 144  */
 145 static int ext2_open_file (struct inode * inode, struct file * filp)
 146 {
 147         if (inode->u.ext2_i.i_high_size && (filp->f_mode & FMODE_WRITE))
 148                 return -EFBIG;
 149         return 0;
 150 }
 151 #endif
 152
 153 /*
 154  * We have mostly NULL's here: the current defaults are ok for
 155  * the ext2 filesystem.
 156  */
 157 static struct file_operations ext2_file_operations = {
 158         ext2_file_lseek,        /* lseek */
 159         generic_file_read,      /* read */
 160         ext2_file_write,        /* write */
 161         NULL,                   /* readdir - bad */
 162         NULL,                   /* poll - default */
 163         ext2_ioctl,             /* ioctl */
 164         generic_file_mmap,      /* mmap */
 165 #if BITS_PER_LONG == 64
 166         NULL,                   /* no special open is needed */
 167 #else
 168         ext2_open_file,
 169 #endif
 170         NULL,                   /* flush */
 171         ext2_release_file,      /* release */
 172         ext2_sync_file,         /* fsync */
 173         NULL,                   /* fasync */
 174         NULL,                   /* check_media_change */
 175         NULL                    /* revalidate */
 176 };
 177
 178 struct inode_operations ext2_file_inode_operations = {
 179         &ext2_file_operations,/* default file operations */
 180         NULL,                   /* create */
 181         NULL,                   /* lookup */
 182         NULL,                   /* link */
 183         NULL,                   /* unlink */
 184         NULL,                   /* symlink */
 185         NULL,                   /* mkdir */
 186         NULL,                   /* rmdir */
 187         NULL,                   /* mknod */
 188         NULL,                   /* rename */
 189         NULL,                   /* readlink */
 190         NULL,                   /* follow_link */
 191         generic_readpage,       /* readpage */
 192         ext2_writepage,         /* writepage */
 193         ext2_bmap,              /* bmap */
 194         ext2_truncate,          /* truncate */
 195         ext2_permission,        /* permission */
 196         NULL,                   /* smap */
 197         NULL,                   /* updatepage */
 198         NULL,                   /* revalidate */
 199         generic_block_flushpage,/* flushpage */
 200 };