Commit 3d5cd491 authored by Amir Goldstein's avatar Amir Goldstein Committed by Christian Brauner
Browse files

fs: create file_write_started() helper 



Convenience wrapper for sb_write_started(file_inode(inode)->i_sb)), which
has a single occurrence in the code right now.

Document the false negatives of those helpers, which makes them unusable
to assert that sb_start_write() is not held.

Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20231122122715.2561213-16-amir73il@gmail.com


Reviewed-by: default avatarJosef Bacik <josef@toxicpanda.com>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 8802e580

fs/read_write.c

+1 −1
Original line number Diff line number Diff line
@@ -1423,7 +1423,7 @@ ssize_t generic_copy_file_range(struct file *file_in, loff_t pos_in, 
				struct file *file_out, loff_t pos_out,

				size_t len, unsigned int flags)

{

	lockdep_assert(sb_write_started(file_inode(file_out)->i_sb));

	lockdep_assert(file_write_started(file_out));



	return do_splice_direct(file_in, &pos_in, file_out, &pos_out,

				len > MAX_RW_COUNT ? MAX_RW_COUNT : len, 0);

include/linux/fs.h

+21 −0
Original line number Diff line number Diff line
@@ -1659,11 +1659,32 @@ static inline int __sb_write_started(const struct super_block *sb, int level) 
	return lockdep_is_held_type(sb->s_writers.rw_sem + level - 1, 1);

}



/**

 * sb_write_started - check if SB_FREEZE_WRITE is held

 * @sb: the super we write to

 *

 * May be false positive with !CONFIG_LOCKDEP/LOCK_STATE_UNKNOWN.

 */

static inline bool sb_write_started(const struct super_block *sb)

{

	return __sb_write_started(sb, SB_FREEZE_WRITE);

}



/**

 * file_write_started - check if SB_FREEZE_WRITE is held

 * @file: the file we write to

 *

 * May be false positive with !CONFIG_LOCKDEP/LOCK_STATE_UNKNOWN.

 * May be false positive with !S_ISREG, because file_start_write() has

 * no effect on !S_ISREG.

 */

static inline bool file_write_started(const struct file *file)

{

	if (!S_ISREG(file_inode(file)->i_mode))

		return true;

	return sb_write_started(file_inode(file)->i_sb);

}



/**

 * sb_end_write - drop write access to a superblock

 * @sb: the super we wrote to