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   1 /*
   2  *  linux/fs/ext4/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  *  ext4 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/time.h>
  22 #include <linux/fs.h>
  23 #include <linux/jbd2.h>
  24 #include "ext4.h"
  25 #include "ext4_jbd2.h"
  26 #include "xattr.h"
  27 #include "acl.h"
  28
  29 /*
  30  * Called when an inode is released. Note that this is different
  31  * from ext4_file_open: open gets called at every open, but release
  32  * gets called only when /all/ the files are closed.
  33  */
  34 static int ext4_release_file(struct inode *inode, struct file *filp)
  35 {
  36         /* if we are the last writer on the inode, drop the block reservation */
  37         if ((filp->f_mode & FMODE_WRITE) &&
  38                         (atomic_read(&inode->i_writecount) == 1))
  39         {
  40                 down_write(&EXT4_I(inode)->i_data_sem);
  41                 ext4_discard_preallocations(inode);
  42                 up_write(&EXT4_I(inode)->i_data_sem);
  43         }
  44         if (is_dx(inode) && filp->private_data)
  45                 ext4_htree_free_dir_info(filp->private_data);
  46
  47         return 0;
  48 }
  49
  50 static ssize_t
  51 ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
  52                 unsigned long nr_segs, loff_t pos)
  53 {
  54         struct file *file = iocb->ki_filp;
  55         struct inode *inode = file->f_path.dentry->d_inode;
  56         ssize_t ret;
  57         int err;
  58
  59         /*
  60          * If we have encountered a bitmap-format file, the size limit
  61          * is smaller than s_maxbytes, which is for extent-mapped files.
  62          */
  63
  64         if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)) {
  65                 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
  66                 size_t length = iov_length(iov, nr_segs);
  67
  68                 if (pos > sbi->s_bitmap_maxbytes)
  69                         return -EFBIG;
  70
  71                 if (pos + length > sbi->s_bitmap_maxbytes) {
  72                         nr_segs = iov_shorten((struct iovec *)iov, nr_segs,
  73                                               sbi->s_bitmap_maxbytes - pos);
  74                 }
  75         }
  76
  77         ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
  78         /*
  79          * Skip flushing if there was an error, or if nothing was written.
  80          */
  81         if (ret <= 0)
  82                 return ret;
  83
  84         /*
  85          * If the inode is IS_SYNC, or is O_SYNC and we are doing data
  86          * journalling then we need to make sure that we force the transaction
  87          * to disk to keep all metadata uptodate synchronously.
  88          */
  89         if (file->f_flags & O_SYNC) {
  90                 /*
  91                  * If we are non-data-journaled, then the dirty data has
  92                  * already been flushed to backing store by generic_osync_inode,
  93                  * and the inode has been flushed too if there have been any
  94                  * modifications other than mere timestamp updates.
  95                  *
  96                  * Open question --- do we care about flushing timestamps too
  97                  * if the inode is IS_SYNC?
  98                  */
  99                 if (!ext4_should_journal_data(inode))
 100                         return ret;
 101
 102                 goto force_commit;
 103         }
 104
 105         /*
 106          * So we know that there has been no forced data flush.  If the inode
 107          * is marked IS_SYNC, we need to force one ourselves.
 108          */
 109         if (!IS_SYNC(inode))
 110                 return ret;
 111
 112         /*
 113          * Open question #2 --- should we force data to disk here too?  If we
 114          * don't, the only impact is that data=writeback filesystems won't
 115          * flush data to disk automatically on IS_SYNC, only metadata (but
 116          * historically, that is what ext2 has done.)
 117          */
 118
 119 force_commit:
 120         err = ext4_force_commit(inode->i_sb);
 121         if (err)
 122                 return err;
 123         return ret;
 124 }
 125
 126 static struct vm_operations_struct ext4_file_vm_ops = {
 127         .fault          = filemap_fault,
 128         .page_mkwrite   = ext4_page_mkwrite,
 129 };
 130
 131 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
 132 {
 133         struct address_space *mapping = file->f_mapping;
 134
 135         if (!mapping->a_ops->readpage)
 136                 return -ENOEXEC;
 137         file_accessed(file);
 138         vma->vm_ops = &ext4_file_vm_ops;
 139         vma->vm_flags |= VM_CAN_NONLINEAR;
 140         return 0;
 141 }
 142
 143 const struct file_operations ext4_file_operations = {
 144         .llseek         = generic_file_llseek,
 145         .read           = do_sync_read,
 146         .write          = do_sync_write,
 147         .aio_read       = generic_file_aio_read,
 148         .aio_write      = ext4_file_write,
 149         .unlocked_ioctl = ext4_ioctl,
 150 #ifdef CONFIG_COMPAT
 151         .compat_ioctl   = ext4_compat_ioctl,
 152 #endif
 153         .mmap           = ext4_file_mmap,
 154         .open           = generic_file_open,
 155         .release        = ext4_release_file,
 156         .fsync          = ext4_sync_file,
 157         .splice_read    = generic_file_splice_read,
 158         .splice_write   = generic_file_splice_write,
 159 };
 160
 161 const struct inode_operations ext4_file_inode_operations = {
 162         .truncate       = ext4_truncate,
 163         .setattr        = ext4_setattr,
 164         .getattr        = ext4_getattr,
 165 #ifdef CONFIG_EXT4_FS_XATTR
 166         .setxattr       = generic_setxattr,
 167         .getxattr       = generic_getxattr,
 168         .listxattr      = ext4_listxattr,
 169         .removexattr    = generic_removexattr,
 170 #endif
 171         .permission     = ext4_permission,
 172         .fallocate      = ext4_fallocate,
 173         .fiemap         = ext4_fiemap,
 174 };
 175