fs/ext2/file.c

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 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 <linux/fs.h>
 22 #include <linux/ext2_fs.h>
 23 #include <linux/sched.h>
 24
 25 static loff_t ext2_file_lseek(struct file *, loff_t,int);
 26 static intext2_open_file(struct inode *,struct file *);
 27
 28 #define EXT2_MAX_SIZE(bits) \
 29  (((EXT2_NDIR_BLOCKS + (1LL << (bits - 2)) + \
 30  (1LL << (bits - 2)) * (1LL << (bits - 2)) + \
 31  (1LL << (bits - 2)) * (1LL << (bits - 2)) * (1LL << (bits - 2))) * \
 32  (1LL << bits)) - 1)
 33
 34 static long long ext2_max_sizes[] = {
 35 0,0,0,0,0,0,0,0,0,0,
 36 EXT2_MAX_SIZE(10),EXT2_MAX_SIZE(11),EXT2_MAX_SIZE(12),EXT2_MAX_SIZE(13)
 37 };
 38
 39 /*
 40  * Make sure the offset never goes beyond the 32-bit mark..
 41  */
 42 static loff_t ext2_file_lseek(
 43 struct file *file,
 44  loff_t offset,
 45 int origin)
 46 {
 47 struct inode *inode = file->f_dentry->d_inode;
 48
 49 switch(origin) {
 50 case2:
 51  offset += inode->i_size;
 52 break;
 53 case1:
 54  offset += file->f_pos;
 55 }
 56 if(offset<0)
 57 return-EINVAL;
 58 if(((unsigned long long) offset >>32) !=0) {
 59 if(offset > ext2_max_sizes[EXT2_BLOCK_SIZE_BITS(inode->i_sb)])
 60 return-EINVAL;
 61 }
 62 if(offset != file->f_pos) {
 63  file->f_pos = offset;
 64  file->f_reada =0;
 65  file->f_version = ++event;
 66 }
 67 return offset;
 68 }
 69
 70 /*
 71  * Called when an inode is released. Note that this is different
 72  * from ext2_file_open: open gets called at every open, but release
 73  * gets called only when /all/ the files are closed.
 74  */
 75 static intext2_release_file(struct inode * inode,struct file * filp)
 76 {
 77 if(filp->f_mode & FMODE_WRITE)
 78 ext2_discard_prealloc(inode);
 79 return0;
 80 }
 81
 82 /*
 83  * Called when an inode is about to be open.
 84  * We use this to disallow opening RW large files on 32bit systems if
 85  * the caller didn't specify O_LARGEFILE. On 64bit systems we force
 86  * on this flag in sys_open.
 87  */
 88 static intext2_open_file(struct inode * inode,struct file * filp)
 89 {
 90 if(!(filp->f_flags & O_LARGEFILE) &&
 91  inode->i_size >0x7FFFFFFFLL)
 92 return-EFBIG;
 93 return0;
 94 }
 95
 96 /*
 97  * We have mostly NULL's here: the current defaults are ok for
 98  * the ext2 filesystem.
 99  */
 100 struct file_operations ext2_file_operations = {
 101  llseek: ext2_file_lseek,
 102  read: generic_file_read,
 103  write: generic_file_write,
 104  ioctl: ext2_ioctl,
 105  mmap: generic_file_mmap,
 106  open: ext2_open_file,
 107  release: ext2_release_file,
 108  fsync: ext2_sync_file,
 109 };
 110
 111 struct inode_operations ext2_file_inode_operations = {
 112  truncate: ext2_truncate,
 113 };