fs: add sync_file_range() helper (22f96b38) · Commits · 戴 / test

fs/sync.c

+71 −64

Original line number	Diff line number	Diff line
		@@ -234,58 +234,10 @@ SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
		return do_fsync(fd, 1);
		}

		/*
		* sys_sync_file_range() permits finely controlled syncing over a segment of
		* a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is
		* zero then sys_sync_file_range() will operate from offset out to EOF.
		*
		* The flag bits are:
		*
		* SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
		* before performing the write.
		*
		* SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
		* range which are not presently under writeback. Note that this may block for
		* significant periods due to exhaustion of disk request structures.
		*
		* SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
		* after performing the write.
		*
		* Useful combinations of the flag bits are:
		*
		* SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE: ensures that all pages
		* in the range which were dirty on entry to sys_sync_file_range() are placed
		* under writeout. This is a start-write-for-data-integrity operation.
		*
		* SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
		* are not presently under writeout. This is an asynchronous flush-to-disk
		* operation. Not suitable for data integrity operations.
		*
		* SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
		* completion of writeout of all pages in the range. This will be used after an
		* earlier SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE operation to wait
		* for that operation to complete and to return the result.
		*
		* SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE\|SYNC_FILE_RANGE_WAIT_AFTER:
		* a traditional sync() operation. This is a write-for-data-integrity operation
		* which will ensure that all pages in the range which were dirty on entry to
		* sys_sync_file_range() are committed to disk.
		*
		*
		* SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
		* I/O errors or ENOSPC conditions and will return those to the caller, after
		* clearing the EIO and ENOSPC flags in the address_space.
		*
		* It should be noted that none of these operations write out the file's
		* metadata. So unless the application is strictly performing overwrites of
		* already-instantiated disk blocks, there are no guarantees here that the data
		* will be available after a crash.
		*/
		int ksys_sync_file_range(int fd, loff_t offset, loff_t nbytes,
		int sync_file_range(struct file *file, loff_t offset, loff_t nbytes,
		unsigned int flags)
		{
		int ret;
		struct fd f;
		struct address_space *mapping;
		loff_t endbyte; /* inclusive */
		umode_t i_mode;
		@@ -325,41 +277,96 @@ int ksys_sync_file_range(int fd, loff_t offset, loff_t nbytes,
		else
		endbyte--; /* inclusive */

		ret = -EBADF;
		f = fdget(fd);
		if (!f.file)
		goto out;

		i_mode = file_inode(f.file)->i_mode;
		i_mode = file_inode(file)->i_mode;
		ret = -ESPIPE;
		if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
		!S_ISLNK(i_mode))
		goto out_put;
		goto out;

		mapping = f.file->f_mapping;
		mapping = file->f_mapping;
		ret = 0;
		if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
		ret = file_fdatawait_range(f.file, offset, endbyte);
		ret = file_fdatawait_range(file, offset, endbyte);
		if (ret < 0)
		goto out_put;
		goto out;
		}

		if (flags & SYNC_FILE_RANGE_WRITE) {
		ret = __filemap_fdatawrite_range(mapping, offset, endbyte,
		WB_SYNC_NONE);
		if (ret < 0)
		goto out_put;
		goto out;
		}

		if (flags & SYNC_FILE_RANGE_WAIT_AFTER)
		ret = file_fdatawait_range(f.file, offset, endbyte);
		ret = file_fdatawait_range(file, offset, endbyte);

		out_put:
		fdput(f);
		out:
		return ret;
		}

		/*
		* sys_sync_file_range() permits finely controlled syncing over a segment of
		* a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is
		* zero then sys_sync_file_range() will operate from offset out to EOF.
		*
		* The flag bits are:
		*
		* SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
		* before performing the write.
		*
		* SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
		* range which are not presently under writeback. Note that this may block for
		* significant periods due to exhaustion of disk request structures.
		*
		* SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
		* after performing the write.
		*
		* Useful combinations of the flag bits are:
		*
		* SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE: ensures that all pages
		* in the range which were dirty on entry to sys_sync_file_range() are placed
		* under writeout. This is a start-write-for-data-integrity operation.
		*
		* SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
		* are not presently under writeout. This is an asynchronous flush-to-disk
		* operation. Not suitable for data integrity operations.
		*
		* SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
		* completion of writeout of all pages in the range. This will be used after an
		* earlier SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE operation to wait
		* for that operation to complete and to return the result.
		*
		* SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE\|SYNC_FILE_RANGE_WAIT_AFTER:
		* a traditional sync() operation. This is a write-for-data-integrity operation
		* which will ensure that all pages in the range which were dirty on entry to
		* sys_sync_file_range() are committed to disk.
		*
		*
		* SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
		* I/O errors or ENOSPC conditions and will return those to the caller, after
		* clearing the EIO and ENOSPC flags in the address_space.
		*
		* It should be noted that none of these operations write out the file's
		* metadata. So unless the application is strictly performing overwrites of
		* already-instantiated disk blocks, there are no guarantees here that the data
		* will be available after a crash.
		*/
		int ksys_sync_file_range(int fd, loff_t offset, loff_t nbytes,
		unsigned int flags)
		{
		int ret;
		struct fd f;

		ret = -EBADF;
		f = fdget(fd);
		if (f.file)
		ret = sync_file_range(f.file, offset, nbytes, flags);

		fdput(f);
		return ret;
		}

		SYSCALL_DEFINE4(sync_file_range, int, fd, loff_t, offset, loff_t, nbytes,
		unsigned int, flags)
		{

include/linux/fs.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -2785,6 +2785,9 @@ extern int vfs_fsync_range(struct file *file, loff_t start, loff_t end,
		int datasync);
		extern int vfs_fsync(struct file *file, int datasync);

		extern int sync_file_range(struct file *file, loff_t offset, loff_t nbytes,
		unsigned int flags);

		/*
		* Sync the bytes written if this was a synchronous write. Expect ki_pos
		* to already be updated for the write, and will return either the amount

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