278 lines
6.8 KiB
C
278 lines
6.8 KiB
C
/*
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* High-level sync()-related operations
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*/
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#include <linux/kernel.h>
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#include <linux/file.h>
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#include <linux/fs.h>
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#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/writeback.h>
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#include <linux/syscalls.h>
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#include <linux/linkage.h>
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#include <linux/pagemap.h>
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#include <linux/quotaops.h>
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#include <linux/buffer_head.h>
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#define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
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SYNC_FILE_RANGE_WAIT_AFTER)
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/*
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* sync everything. Start out by waking pdflush, because that writes back
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* all queues in parallel.
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*/
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static void do_sync(unsigned long wait)
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{
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wakeup_pdflush(0);
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sync_inodes(0); /* All mappings, inodes and their blockdevs */
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DQUOT_SYNC(NULL);
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sync_supers(); /* Write the superblocks */
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sync_filesystems(0); /* Start syncing the filesystems */
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sync_filesystems(wait); /* Waitingly sync the filesystems */
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sync_inodes(wait); /* Mappings, inodes and blockdevs, again. */
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if (!wait)
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printk("Emergency Sync complete\n");
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if (unlikely(laptop_mode))
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laptop_sync_completion();
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}
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asmlinkage long sys_sync(void)
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{
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do_sync(1);
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return 0;
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}
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void emergency_sync(void)
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{
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pdflush_operation(do_sync, 0);
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}
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/*
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* Generic function to fsync a file.
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*
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* filp may be NULL if called via the msync of a vma.
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*/
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int file_fsync(struct file *filp, struct dentry *dentry, int datasync)
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{
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struct inode * inode = dentry->d_inode;
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struct super_block * sb;
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int ret, err;
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/* sync the inode to buffers */
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ret = write_inode_now(inode, 0);
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/* sync the superblock to buffers */
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sb = inode->i_sb;
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lock_super(sb);
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if (sb->s_op->write_super)
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sb->s_op->write_super(sb);
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unlock_super(sb);
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/* .. finally sync the buffers to disk */
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err = sync_blockdev(sb->s_bdev);
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if (!ret)
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ret = err;
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return ret;
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}
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long do_fsync(struct file *file, int datasync)
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{
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int ret;
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int err;
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struct address_space *mapping = file->f_mapping;
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if (!file->f_op || !file->f_op->fsync) {
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/* Why? We can still call filemap_fdatawrite */
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ret = -EINVAL;
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goto out;
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}
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ret = filemap_fdatawrite(mapping);
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/*
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* We need to protect against concurrent writers, which could cause
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* livelocks in fsync_buffers_list().
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*/
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mutex_lock(&mapping->host->i_mutex);
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err = file->f_op->fsync(file, file->f_dentry, datasync);
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if (!ret)
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ret = err;
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mutex_unlock(&mapping->host->i_mutex);
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err = filemap_fdatawait(mapping);
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if (!ret)
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ret = err;
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out:
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return ret;
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}
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static long __do_fsync(unsigned int fd, int datasync)
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{
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struct file *file;
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int ret = -EBADF;
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file = fget(fd);
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if (file) {
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ret = do_fsync(file, datasync);
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fput(file);
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}
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return ret;
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}
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asmlinkage long sys_fsync(unsigned int fd)
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{
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return __do_fsync(fd, 0);
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}
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asmlinkage long sys_fdatasync(unsigned int fd)
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{
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return __do_fsync(fd, 1);
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}
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/*
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* sys_sync_file_range() permits finely controlled syncing over a segment of
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* a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is
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* zero then sys_sync_file_range() will operate from offset out to EOF.
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*
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* The flag bits are:
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*
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* SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
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* before performing the write.
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*
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* SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
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* range which are not presently under writeback.
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*
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* SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
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* after performing the write.
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*
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* Useful combinations of the flag bits are:
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*
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* SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages
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* in the range which were dirty on entry to sys_sync_file_range() are placed
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* under writeout. This is a start-write-for-data-integrity operation.
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*
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* SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
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* are not presently under writeout. This is an asynchronous flush-to-disk
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* operation. Not suitable for data integrity operations.
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*
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* SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
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* completion of writeout of all pages in the range. This will be used after an
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* earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait
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* for that operation to complete and to return the result.
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*
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* SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER:
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* a traditional sync() operation. This is a write-for-data-integrity operation
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* which will ensure that all pages in the range which were dirty on entry to
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* sys_sync_file_range() are committed to disk.
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*
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*
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* SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
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* I/O errors or ENOSPC conditions and will return those to the caller, after
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* clearing the EIO and ENOSPC flags in the address_space.
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*
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* It should be noted that none of these operations write out the file's
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* metadata. So unless the application is strictly performing overwrites of
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* already-instantiated disk blocks, there are no guarantees here that the data
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* will be available after a crash.
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*/
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asmlinkage long sys_sync_file_range(int fd, loff_t offset, loff_t nbytes,
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unsigned int flags)
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{
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int ret;
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struct file *file;
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loff_t endbyte; /* inclusive */
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int fput_needed;
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umode_t i_mode;
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ret = -EINVAL;
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if (flags & ~VALID_FLAGS)
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goto out;
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endbyte = offset + nbytes;
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if ((s64)offset < 0)
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goto out;
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if ((s64)endbyte < 0)
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goto out;
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if (endbyte < offset)
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goto out;
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if (sizeof(pgoff_t) == 4) {
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if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
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/*
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* The range starts outside a 32 bit machine's
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* pagecache addressing capabilities. Let it "succeed"
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*/
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ret = 0;
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goto out;
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}
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if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
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/*
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* Out to EOF
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*/
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nbytes = 0;
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}
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}
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if (nbytes == 0)
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endbyte = LLONG_MAX;
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else
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endbyte--; /* inclusive */
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ret = -EBADF;
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file = fget_light(fd, &fput_needed);
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if (!file)
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goto out;
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i_mode = file->f_dentry->d_inode->i_mode;
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ret = -ESPIPE;
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if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
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!S_ISLNK(i_mode))
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goto out_put;
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ret = do_sync_file_range(file, offset, endbyte, flags);
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out_put:
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fput_light(file, fput_needed);
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out:
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return ret;
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}
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/*
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* `endbyte' is inclusive
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*/
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int do_sync_file_range(struct file *file, loff_t offset, loff_t endbyte,
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unsigned int flags)
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{
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int ret;
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struct address_space *mapping;
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mapping = file->f_mapping;
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if (!mapping) {
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ret = -EINVAL;
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goto out;
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}
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ret = 0;
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if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
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ret = wait_on_page_writeback_range(mapping,
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offset >> PAGE_CACHE_SHIFT,
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endbyte >> PAGE_CACHE_SHIFT);
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if (ret < 0)
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goto out;
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}
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if (flags & SYNC_FILE_RANGE_WRITE) {
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ret = __filemap_fdatawrite_range(mapping, offset, endbyte,
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WB_SYNC_NONE);
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if (ret < 0)
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goto out;
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}
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if (flags & SYNC_FILE_RANGE_WAIT_AFTER) {
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ret = wait_on_page_writeback_range(mapping,
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offset >> PAGE_CACHE_SHIFT,
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endbyte >> PAGE_CACHE_SHIFT);
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}
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out:
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return ret;
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}
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EXPORT_SYMBOL_GPL(do_sync_file_range);
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