linux/fs/logfs/file.c
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   1/*
   2 * fs/logfs/file.c      - prepare_write, commit_write and friends
   3 *
   4 * As should be obvious for Linux kernel code, license is GPLv2
   5 *
   6 * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
   7 */
   8#include "logfs.h"
   9#include <linux/sched.h>
  10#include <linux/writeback.h>
  11
  12static int logfs_write_begin(struct file *file, struct address_space *mapping,
  13                loff_t pos, unsigned len, unsigned flags,
  14                struct page **pagep, void **fsdata)
  15{
  16        struct inode *inode = mapping->host;
  17        struct page *page;
  18        pgoff_t index = pos >> PAGE_CACHE_SHIFT;
  19
  20        page = grab_cache_page_write_begin(mapping, index, flags);
  21        if (!page)
  22                return -ENOMEM;
  23        *pagep = page;
  24
  25        if ((len == PAGE_CACHE_SIZE) || PageUptodate(page))
  26                return 0;
  27        if ((pos & PAGE_CACHE_MASK) >= i_size_read(inode)) {
  28                unsigned start = pos & (PAGE_CACHE_SIZE - 1);
  29                unsigned end = start + len;
  30
  31                /* Reading beyond i_size is simple: memset to zero */
  32                zero_user_segments(page, 0, start, end, PAGE_CACHE_SIZE);
  33                return 0;
  34        }
  35        return logfs_readpage_nolock(page);
  36}
  37
  38static int logfs_write_end(struct file *file, struct address_space *mapping,
  39                loff_t pos, unsigned len, unsigned copied, struct page *page,
  40                void *fsdata)
  41{
  42        struct inode *inode = mapping->host;
  43        pgoff_t index = page->index;
  44        unsigned start = pos & (PAGE_CACHE_SIZE - 1);
  45        unsigned end = start + copied;
  46        int ret = 0;
  47
  48        BUG_ON(PAGE_CACHE_SIZE != inode->i_sb->s_blocksize);
  49        BUG_ON(page->index > I3_BLOCKS);
  50
  51        if (copied < len) {
  52                /*
  53                 * Short write of a non-initialized paged.  Just tell userspace
  54                 * to retry the entire page.
  55                 */
  56                if (!PageUptodate(page)) {
  57                        copied = 0;
  58                        goto out;
  59                }
  60        }
  61        if (copied == 0)
  62                goto out; /* FIXME: do we need to update inode? */
  63
  64        if (i_size_read(inode) < (index << PAGE_CACHE_SHIFT) + end) {
  65                i_size_write(inode, (index << PAGE_CACHE_SHIFT) + end);
  66                mark_inode_dirty_sync(inode);
  67        }
  68
  69        SetPageUptodate(page);
  70        if (!PageDirty(page)) {
  71                if (!get_page_reserve(inode, page))
  72                        __set_page_dirty_nobuffers(page);
  73                else
  74                        ret = logfs_write_buf(inode, page, WF_LOCK);
  75        }
  76out:
  77        unlock_page(page);
  78        page_cache_release(page);
  79        return ret ? ret : copied;
  80}
  81
  82int logfs_readpage(struct file *file, struct page *page)
  83{
  84        int ret;
  85
  86        ret = logfs_readpage_nolock(page);
  87        unlock_page(page);
  88        return ret;
  89}
  90
  91/* Clear the page's dirty flag in the radix tree. */
  92/* TODO: mucking with PageWriteback is silly.  Add a generic function to clear
  93 * the dirty bit from the radix tree for filesystems that don't have to wait
  94 * for page writeback to finish (i.e. any compressing filesystem).
  95 */
  96static void clear_radix_tree_dirty(struct page *page)
  97{
  98        BUG_ON(PagePrivate(page) || page->private);
  99        set_page_writeback(page);
 100        end_page_writeback(page);
 101}
 102
 103static int __logfs_writepage(struct page *page)
 104{
 105        struct inode *inode = page->mapping->host;
 106        int err;
 107
 108        err = logfs_write_buf(inode, page, WF_LOCK);
 109        if (err)
 110                set_page_dirty(page);
 111        else
 112                clear_radix_tree_dirty(page);
 113        unlock_page(page);
 114        return err;
 115}
 116
 117static int logfs_writepage(struct page *page, struct writeback_control *wbc)
 118{
 119        struct inode *inode = page->mapping->host;
 120        loff_t i_size = i_size_read(inode);
 121        pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
 122        unsigned offset;
 123        u64 bix;
 124        level_t level;
 125
 126        log_file("logfs_writepage(%lx, %lx, %p)\n", inode->i_ino, page->index,
 127                        page);
 128
 129        logfs_unpack_index(page->index, &bix, &level);
 130
 131        /* Indirect blocks are never truncated */
 132        if (level != 0)
 133                return __logfs_writepage(page);
 134
 135        /*
 136         * TODO: everything below is a near-verbatim copy of nobh_writepage().
 137         * The relevant bits should be factored out after logfs is merged.
 138         */
 139
 140        /* Is the page fully inside i_size? */
 141        if (bix < end_index)
 142                return __logfs_writepage(page);
 143
 144         /* Is the page fully outside i_size? (truncate in progress) */
 145        offset = i_size & (PAGE_CACHE_SIZE-1);
 146        if (bix > end_index || offset == 0) {
 147                unlock_page(page);
 148                return 0; /* don't care */
 149        }
 150
 151        /*
 152         * The page straddles i_size.  It must be zeroed out on each and every
 153         * writepage invokation because it may be mmapped.  "A file is mapped
 154         * in multiples of the page size.  For a file that is not a multiple of
 155         * the  page size, the remaining memory is zeroed when mapped, and
 156         * writes to that region are not written out to the file."
 157         */
 158        zero_user_segment(page, offset, PAGE_CACHE_SIZE);
 159        return __logfs_writepage(page);
 160}
 161
 162static void logfs_invalidatepage(struct page *page, unsigned long offset)
 163{
 164        struct logfs_block *block = logfs_block(page);
 165
 166        if (block->reserved_bytes) {
 167                struct super_block *sb = page->mapping->host->i_sb;
 168                struct logfs_super *super = logfs_super(sb);
 169
 170                super->s_dirty_pages -= block->reserved_bytes;
 171                block->ops->free_block(sb, block);
 172                BUG_ON(bitmap_weight(block->alias_map, LOGFS_BLOCK_FACTOR));
 173        } else
 174                move_page_to_btree(page);
 175        BUG_ON(PagePrivate(page) || page->private);
 176}
 177
 178static int logfs_releasepage(struct page *page, gfp_t only_xfs_uses_this)
 179{
 180        return 0; /* None of these are easy to release */
 181}
 182
 183
 184long logfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 185{
 186        struct inode *inode = file->f_path.dentry->d_inode;
 187        struct logfs_inode *li = logfs_inode(inode);
 188        unsigned int oldflags, flags;
 189        int err;
 190
 191        switch (cmd) {
 192        case FS_IOC_GETFLAGS:
 193                flags = li->li_flags & LOGFS_FL_USER_VISIBLE;
 194                return put_user(flags, (int __user *)arg);
 195        case FS_IOC_SETFLAGS:
 196                if (IS_RDONLY(inode))
 197                        return -EROFS;
 198
 199                if (!inode_owner_or_capable(inode))
 200                        return -EACCES;
 201
 202                err = get_user(flags, (int __user *)arg);
 203                if (err)
 204                        return err;
 205
 206                mutex_lock(&inode->i_mutex);
 207                oldflags = li->li_flags;
 208                flags &= LOGFS_FL_USER_MODIFIABLE;
 209                flags |= oldflags & ~LOGFS_FL_USER_MODIFIABLE;
 210                li->li_flags = flags;
 211                mutex_unlock(&inode->i_mutex);
 212
 213                inode->i_ctime = CURRENT_TIME;
 214                mark_inode_dirty_sync(inode);
 215                return 0;
 216
 217        default:
 218                return -ENOTTY;
 219        }
 220}
 221
 222int logfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 223{
 224        struct super_block *sb = file->f_mapping->host->i_sb;
 225        struct inode *inode = file->f_mapping->host;
 226        int ret;
 227
 228        ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
 229        if (ret)
 230                return ret;
 231
 232        mutex_lock(&inode->i_mutex);
 233        logfs_get_wblocks(sb, NULL, WF_LOCK);
 234        logfs_write_anchor(sb);
 235        logfs_put_wblocks(sb, NULL, WF_LOCK);
 236        mutex_unlock(&inode->i_mutex);
 237
 238        return 0;
 239}
 240
 241static int logfs_setattr(struct dentry *dentry, struct iattr *attr)
 242{
 243        struct inode *inode = dentry->d_inode;
 244        int err = 0;
 245
 246        err = inode_change_ok(inode, attr);
 247        if (err)
 248                return err;
 249
 250        if (attr->ia_valid & ATTR_SIZE) {
 251                err = logfs_truncate(inode, attr->ia_size);
 252                if (err)
 253                        return err;
 254        }
 255
 256        setattr_copy(inode, attr);
 257        mark_inode_dirty(inode);
 258        return 0;
 259}
 260
 261const struct inode_operations logfs_reg_iops = {
 262        .setattr        = logfs_setattr,
 263};
 264
 265const struct file_operations logfs_reg_fops = {
 266        .aio_read       = generic_file_aio_read,
 267        .aio_write      = generic_file_aio_write,
 268        .fsync          = logfs_fsync,
 269        .unlocked_ioctl = logfs_ioctl,
 270        .llseek         = generic_file_llseek,
 271        .mmap           = generic_file_readonly_mmap,
 272        .open           = generic_file_open,
 273        .read           = do_sync_read,
 274        .write          = do_sync_write,
 275};
 276
 277const struct address_space_operations logfs_reg_aops = {
 278        .invalidatepage = logfs_invalidatepage,
 279        .readpage       = logfs_readpage,
 280        .releasepage    = logfs_releasepage,
 281        .set_page_dirty = __set_page_dirty_nobuffers,
 282        .writepage      = logfs_writepage,
 283        .writepages     = generic_writepages,
 284        .write_begin    = logfs_write_begin,
 285        .write_end      = logfs_write_end,
 286};
 287
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