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fs: create file_write_started() helper

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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: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20231122122715.2561213-16-amir73il@gmail.com
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Amir Goldstein 2023-11-22 14:27:14 +02:00 committed by Christian Brauner
parent 8802e580ee
commit 3d5cd4911e
2 changed files with 22 additions and 1 deletions
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2
fs/read_write.c
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@ -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);

21
include/linux/fs.h
View File

@ -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