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394 lines
10 KiB
394 lines
10 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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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/slab.h> |
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#include <linux/export.h> |
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#include <linux/namei.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/backing-dev.h> |
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#include "internal.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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* Do the filesystem syncing work. For simple filesystems |
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* writeback_inodes_sb(sb) just dirties buffers with inodes so we have to |
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* submit IO for these buffers via __sync_blockdev(). This also speeds up the |
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* wait == 1 case since in that case write_inode() functions do |
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* sync_dirty_buffer() and thus effectively write one block at a time. |
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*/ |
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static int __sync_filesystem(struct super_block *sb, int wait) |
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{ |
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if (wait) |
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sync_inodes_sb(sb); |
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else |
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writeback_inodes_sb(sb, WB_REASON_SYNC); |
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if (sb->s_op->sync_fs) |
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sb->s_op->sync_fs(sb, wait); |
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return __sync_blockdev(sb->s_bdev, wait); |
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} |
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/* |
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* Write out and wait upon all dirty data associated with this |
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* superblock. Filesystem data as well as the underlying block |
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* device. Takes the superblock lock. |
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*/ |
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int sync_filesystem(struct super_block *sb) |
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{ |
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int ret; |
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/* |
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* We need to be protected against the filesystem going from |
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* r/o to r/w or vice versa. |
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*/ |
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WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
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/* |
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* No point in syncing out anything if the filesystem is read-only. |
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*/ |
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if (sb_rdonly(sb)) |
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return 0; |
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ret = __sync_filesystem(sb, 0); |
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if (ret < 0) |
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return ret; |
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return __sync_filesystem(sb, 1); |
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} |
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EXPORT_SYMBOL(sync_filesystem); |
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static void sync_inodes_one_sb(struct super_block *sb, void *arg) |
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{ |
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if (!sb_rdonly(sb)) |
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sync_inodes_sb(sb); |
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} |
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static void sync_fs_one_sb(struct super_block *sb, void *arg) |
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{ |
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if (!sb_rdonly(sb) && !(sb->s_iflags & SB_I_SKIP_SYNC) && |
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sb->s_op->sync_fs) |
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sb->s_op->sync_fs(sb, *(int *)arg); |
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} |
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static void fdatawrite_one_bdev(struct block_device *bdev, void *arg) |
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{ |
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filemap_fdatawrite(bdev->bd_inode->i_mapping); |
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} |
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static void fdatawait_one_bdev(struct block_device *bdev, void *arg) |
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{ |
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/* |
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* We keep the error status of individual mapping so that |
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* applications can catch the writeback error using fsync(2). |
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* See filemap_fdatawait_keep_errors() for details. |
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*/ |
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filemap_fdatawait_keep_errors(bdev->bd_inode->i_mapping); |
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} |
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/* |
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* Sync everything. We start by waking flusher threads so that most of |
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* writeback runs on all devices in parallel. Then we sync all inodes reliably |
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* which effectively also waits for all flusher threads to finish doing |
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* writeback. At this point all data is on disk so metadata should be stable |
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* and we tell filesystems to sync their metadata via ->sync_fs() calls. |
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* Finally, we writeout all block devices because some filesystems (e.g. ext2) |
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* just write metadata (such as inodes or bitmaps) to block device page cache |
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* and do not sync it on their own in ->sync_fs(). |
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*/ |
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void ksys_sync(void) |
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{ |
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int nowait = 0, wait = 1; |
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wakeup_flusher_threads(WB_REASON_SYNC); |
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iterate_supers(sync_inodes_one_sb, NULL); |
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iterate_supers(sync_fs_one_sb, &nowait); |
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iterate_supers(sync_fs_one_sb, &wait); |
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iterate_bdevs(fdatawrite_one_bdev, NULL); |
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iterate_bdevs(fdatawait_one_bdev, NULL); |
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if (unlikely(laptop_mode)) |
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laptop_sync_completion(); |
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} |
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SYSCALL_DEFINE0(sync) |
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{ |
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ksys_sync(); |
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return 0; |
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} |
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static void do_sync_work(struct work_struct *work) |
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{ |
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int nowait = 0; |
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/* |
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* Sync twice to reduce the possibility we skipped some inodes / pages |
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* because they were temporarily locked |
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*/ |
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iterate_supers(sync_inodes_one_sb, &nowait); |
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iterate_supers(sync_fs_one_sb, &nowait); |
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iterate_bdevs(fdatawrite_one_bdev, NULL); |
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iterate_supers(sync_inodes_one_sb, &nowait); |
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iterate_supers(sync_fs_one_sb, &nowait); |
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iterate_bdevs(fdatawrite_one_bdev, NULL); |
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printk("Emergency Sync complete\n"); |
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kfree(work); |
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} |
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void emergency_sync(void) |
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{ |
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struct work_struct *work; |
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work = kmalloc(sizeof(*work), GFP_ATOMIC); |
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if (work) { |
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INIT_WORK(work, do_sync_work); |
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schedule_work(work); |
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} |
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} |
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/* |
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* sync a single super |
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*/ |
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SYSCALL_DEFINE1(syncfs, int, fd) |
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{ |
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struct fd f = fdget(fd); |
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struct super_block *sb; |
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int ret, ret2; |
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if (!f.file) |
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return -EBADF; |
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sb = f.file->f_path.dentry->d_sb; |
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down_read(&sb->s_umount); |
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ret = sync_filesystem(sb); |
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up_read(&sb->s_umount); |
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ret2 = errseq_check_and_advance(&sb->s_wb_err, &f.file->f_sb_err); |
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fdput(f); |
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return ret ? ret : ret2; |
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} |
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/** |
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* vfs_fsync_range - helper to sync a range of data & metadata to disk |
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* @file: file to sync |
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* @start: offset in bytes of the beginning of data range to sync |
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* @end: offset in bytes of the end of data range (inclusive) |
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* @datasync: perform only datasync |
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* |
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* Write back data in range @start..@end and metadata for @file to disk. If |
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* @datasync is set only metadata needed to access modified file data is |
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* written. |
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*/ |
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int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync) |
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{ |
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struct inode *inode = file->f_mapping->host; |
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if (!file->f_op->fsync) |
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return -EINVAL; |
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if (!datasync && (inode->i_state & I_DIRTY_TIME)) |
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mark_inode_dirty_sync(inode); |
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return file->f_op->fsync(file, start, end, datasync); |
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} |
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EXPORT_SYMBOL(vfs_fsync_range); |
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/** |
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* vfs_fsync - perform a fsync or fdatasync on a file |
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* @file: file to sync |
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* @datasync: only perform a fdatasync operation |
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* |
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* Write back data and metadata for @file to disk. If @datasync is |
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* set only metadata needed to access modified file data is written. |
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*/ |
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int vfs_fsync(struct file *file, int datasync) |
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{ |
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return vfs_fsync_range(file, 0, LLONG_MAX, datasync); |
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} |
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EXPORT_SYMBOL(vfs_fsync); |
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static int do_fsync(unsigned int fd, int datasync) |
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{ |
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struct fd f = fdget(fd); |
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int ret = -EBADF; |
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if (f.file) { |
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ret = vfs_fsync(f.file, datasync); |
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fdput(f); |
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} |
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return ret; |
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} |
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SYSCALL_DEFINE1(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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SYSCALL_DEFINE1(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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int sync_file_range(struct file *file, 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 address_space *mapping; |
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loff_t endbyte; /* inclusive */ |
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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_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_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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i_mode = file_inode(file)->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; |
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mapping = file->f_mapping; |
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ret = 0; |
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if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { |
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ret = file_fdatawait_range(file, offset, endbyte); |
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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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int sync_mode = WB_SYNC_NONE; |
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if ((flags & SYNC_FILE_RANGE_WRITE_AND_WAIT) == |
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SYNC_FILE_RANGE_WRITE_AND_WAIT) |
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sync_mode = WB_SYNC_ALL; |
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ret = __filemap_fdatawrite_range(mapping, offset, endbyte, |
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sync_mode); |
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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 = file_fdatawait_range(file, offset, endbyte); |
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out: |
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return ret; |
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} |
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/* |
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* ksys_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 ksys_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. Note that this may block for |
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* significant periods due to exhaustion of disk request structures. |
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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 ksys_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.k.a. SYNC_FILE_RANGE_WRITE_AND_WAIT): |
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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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* ksys_sync_file_range() are written to disk. It should be noted that disk |
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* caches are not flushed by this call, so there are no guarantees here that the |
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* data will be available on disk after a crash. |
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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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int ksys_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 fd f; |
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ret = -EBADF; |
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f = fdget(fd); |
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if (f.file) |
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ret = sync_file_range(f.file, offset, nbytes, flags); |
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fdput(f); |
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return ret; |
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} |
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SYSCALL_DEFINE4(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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return ksys_sync_file_range(fd, offset, nbytes, flags); |
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} |
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/* It would be nice if people remember that not all the world's an i386 |
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when they introduce new system calls */ |
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SYSCALL_DEFINE4(sync_file_range2, int, fd, unsigned int, flags, |
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loff_t, offset, loff_t, nbytes) |
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{ |
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return ksys_sync_file_range(fd, offset, nbytes, flags); |
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}
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