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 <linux/time.h>
  22 #include <linux/pagemap.h>
  23 #include <linux/dax.h>
  24 #include <linux/quotaops.h>
  25 #include "ext2.h"
  26 #include "xattr.h"
  27 #include "acl.h"
  28
  29 #ifdef CONFIG_FS_DAX
  30 /*
  31  * The lock ordering for ext2 DAX fault paths is:
  32  *
  33  * mmap_sem (MM)
  34  *   sb_start_pagefault (vfs, freeze)
  35  *     ext2_inode_info->dax_sem
  36  *       address_space->i_mmap_rwsem or page_lock (mutually exclusive in DAX)
  37  *         ext2_inode_info->truncate_mutex
  38  *
  39  * The default page_lock and i_size verification done by non-DAX fault paths
  40  * is sufficient because ext2 doesn't support hole punching.
  41  */
  42 static int ext2_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
  43 {
  44         struct inode *inode = file_inode(vma->vm_file);
  45         struct ext2_inode_info *ei = EXT2_I(inode);
  46         int ret;
  47
  48         if (vmf->flags & FAULT_FLAG_WRITE) {
  49                 sb_start_pagefault(inode->i_sb);
  50                 file_update_time(vma->vm_file);
  51         }
  52         down_read(&ei->dax_sem);
  53
  54         ret = dax_fault(vma, vmf, ext2_get_block);
  55
  56         up_read(&ei->dax_sem);
  57         if (vmf->flags & FAULT_FLAG_WRITE)
  58                 sb_end_pagefault(inode->i_sb);
  59         return ret;
  60 }
  61
  62 static int ext2_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
  63                                                 pmd_t *pmd, unsigned int flags)
  64 {
  65         struct inode *inode = file_inode(vma->vm_file);
  66         struct ext2_inode_info *ei = EXT2_I(inode);
  67         int ret;
  68
  69         if (flags & FAULT_FLAG_WRITE) {
  70                 sb_start_pagefault(inode->i_sb);
  71                 file_update_time(vma->vm_file);
  72         }
  73         down_read(&ei->dax_sem);
  74
  75         ret = dax_pmd_fault(vma, addr, pmd, flags, ext2_get_block);
  76
  77         up_read(&ei->dax_sem);
  78         if (flags & FAULT_FLAG_WRITE)
  79                 sb_end_pagefault(inode->i_sb);
  80         return ret;
  81 }
  82
  83 static int ext2_dax_pfn_mkwrite(struct vm_area_struct *vma,
  84                 struct vm_fault *vmf)
  85 {
  86         struct inode *inode = file_inode(vma->vm_file);
  87         struct ext2_inode_info *ei = EXT2_I(inode);
  88         loff_t size;
  89         int ret;
  90
  91         sb_start_pagefault(inode->i_sb);
  92         file_update_time(vma->vm_file);
  93         down_read(&ei->dax_sem);
  94
  95         /* check that the faulting page hasn't raced with truncate */
  96         size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
  97         if (vmf->pgoff >= size)
  98                 ret = VM_FAULT_SIGBUS;
  99         else
 100                 ret = dax_pfn_mkwrite(vma, vmf);
 101
 102         up_read(&ei->dax_sem);
 103         sb_end_pagefault(inode->i_sb);
 104         return ret;
 105 }
 106
 107 static const struct vm_operations_struct ext2_dax_vm_ops = {
 108         .fault          = ext2_dax_fault,
 109         .pmd_fault      = ext2_dax_pmd_fault,
 110         .page_mkwrite   = ext2_dax_fault,
 111         .pfn_mkwrite    = ext2_dax_pfn_mkwrite,
 112 };
 113
 114 static int ext2_file_mmap(struct file *file, struct vm_area_struct *vma)
 115 {
 116         if (!IS_DAX(file_inode(file)))
 117                 return generic_file_mmap(file, vma);
 118
 119         file_accessed(file);
 120         vma->vm_ops = &ext2_dax_vm_ops;
 121         vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
 122         return 0;
 123 }
 124 #else
 125 #define ext2_file_mmap  generic_file_mmap
 126 #endif
 127
 128 /*
 129  * Called when filp is released. This happens when all file descriptors
 130  * for a single struct file are closed. Note that different open() calls
 131  * for the same file yield different struct file structures.
 132  */
 133 static int ext2_release_file (struct inode * inode, struct file * filp)
 134 {
 135         if (filp->f_mode & FMODE_WRITE) {
 136                 mutex_lock(&EXT2_I(inode)->truncate_mutex);
 137                 ext2_discard_reservation(inode);
 138                 mutex_unlock(&EXT2_I(inode)->truncate_mutex);
 139         }
 140         return 0;
 141 }
 142
 143 int ext2_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 144 {
 145         int ret;
 146         struct super_block *sb = file->f_mapping->host->i_sb;
 147         struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
 148
 149         ret = generic_file_fsync(file, start, end, datasync);
 150         if (ret == -EIO || test_and_clear_bit(AS_EIO, &mapping->flags)) {
 151                 /* We don't really know where the IO error happened... */
 152                 ext2_error(sb, __func__,
 153                            "detected IO error when writing metadata buffers");
 154                 ret = -EIO;
 155         }
 156         return ret;
 157 }
 158
 159 /*
 160  * We have mostly NULL's here: the current defaults are ok for
 161  * the ext2 filesystem.
 162  */
 163 const struct file_operations ext2_file_operations = {
 164         .llseek         = generic_file_llseek,
 165         .read_iter      = generic_file_read_iter,
 166         .write_iter     = generic_file_write_iter,
 167         .unlocked_ioctl = ext2_ioctl,
 168 #ifdef CONFIG_COMPAT
 169         .compat_ioctl   = ext2_compat_ioctl,
 170 #endif
 171         .mmap           = ext2_file_mmap,
 172         .open           = dquot_file_open,
 173         .release        = ext2_release_file,
 174         .fsync          = ext2_fsync,
 175         .splice_read    = generic_file_splice_read,
 176         .splice_write   = iter_file_splice_write,
 177 };
 178
 179 const struct inode_operations ext2_file_inode_operations = {
 180 #ifdef CONFIG_EXT2_FS_XATTR
 181         .setxattr       = generic_setxattr,
 182         .getxattr       = generic_getxattr,
 183         .listxattr      = ext2_listxattr,
 184         .removexattr    = generic_removexattr,
 185 #endif
 186         .setattr        = ext2_setattr,
 187         .get_acl        = ext2_get_acl,
 188         .set_acl        = ext2_set_acl,
 189         .fiemap         = ext2_fiemap,
 190 };