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vfs: separate __sb_start_write into blocking and non-blocking helpers 

Break this function into two helpers so that it's obvious that the
trylock versions return a value that must be checked, and the blocking
versions don't require that.  While we're at it, clean up the return
type mismatch.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
pull/193/head
Darrick J. Wong 2020-11-10 16:50:21 -08:00
parent 22843291ef
commit 8a3c84b649
4 changed files with 25 additions and 19 deletions
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2
fs/aio.c
View File

@ -1572,7 +1572,7 @@ static int aio_write(struct kiocb *req, const struct iocb *iocb,
* we return to userspace.
*/
if (S_ISREG(file_inode(file)->i_mode)) {
__sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, true);
sb_start_write(file_inode(file)->i_sb);
__sb_writers_release(file_inode(file)->i_sb, SB_FREEZE_WRITE);
}
req->ki_flags |= IOCB_WRITE;

3
fs/io_uring.c
View File

@ -3532,8 +3532,7 @@ static int io_write(struct io_kiocb *req, bool force_nonblock,
* we return to userspace.
*/
if (req->flags & REQ_F_ISREG) {
__sb_start_write(file_inode(req->file)->i_sb,
SB_FREEZE_WRITE, true);
sb_start_write(file_inode(req->file)->i_sb);
__sb_writers_release(file_inode(req->file)->i_sb,
SB_FREEZE_WRITE);
}

18
fs/super.c
View File

@ -1645,16 +1645,22 @@ EXPORT_SYMBOL(__sb_end_write);
* This is an internal function, please use sb_start_{write,pagefault,intwrite}
* instead.
*/
int __sb_start_write(struct super_block *sb, int level, bool wait)
void __sb_start_write(struct super_block *sb, int level)
{
if (!wait)
return percpu_down_read_trylock(sb->s_writers.rw_sem + level-1);
percpu_down_read(sb->s_writers.rw_sem + level-1);
return 1;
percpu_down_read(sb->s_writers.rw_sem + level - 1);
}
EXPORT_SYMBOL(__sb_start_write);
/*
* This is an internal function, please use sb_start_{write,pagefault,intwrite}
* instead.
*/
bool __sb_start_write_trylock(struct super_block *sb, int level)
{
return percpu_down_read_trylock(sb->s_writers.rw_sem + level - 1);
}
EXPORT_SYMBOL_GPL(__sb_start_write_trylock);
/**
* sb_wait_write - wait until all writers to given file system finish
* @sb: the super for which we wait

21
include/linux/fs.h
View File

@ -1581,7 +1581,8 @@ extern struct timespec64 current_time(struct inode *inode);
*/
void __sb_end_write(struct super_block *sb, int level);
int __sb_start_write(struct super_block *sb, int level, bool wait);
void __sb_start_write(struct super_block *sb, int level);
bool __sb_start_write_trylock(struct super_block *sb, int level);
#define __sb_writers_acquired(sb, lev) \
percpu_rwsem_acquire(&(sb)->s_writers.rw_sem[(lev)-1], 1, _THIS_IP_)
@ -1645,12 +1646,12 @@ static inline void sb_end_intwrite(struct super_block *sb)
*/
static inline void sb_start_write(struct super_block *sb)
{
__sb_start_write(sb, SB_FREEZE_WRITE, true);
__sb_start_write(sb, SB_FREEZE_WRITE);
}
static inline int sb_start_write_trylock(struct super_block *sb)
static inline bool sb_start_write_trylock(struct super_block *sb)
{
return __sb_start_write(sb, SB_FREEZE_WRITE, false);
return __sb_start_write_trylock(sb, SB_FREEZE_WRITE);
}
/**
@ -1674,7 +1675,7 @@ static inline int sb_start_write_trylock(struct super_block *sb)
*/
static inline void sb_start_pagefault(struct super_block *sb)
{
__sb_start_write(sb, SB_FREEZE_PAGEFAULT, true);
__sb_start_write(sb, SB_FREEZE_PAGEFAULT);
}
/*
@ -1692,12 +1693,12 @@ static inline void sb_start_pagefault(struct super_block *sb)
*/
static inline void sb_start_intwrite(struct super_block *sb)
{
__sb_start_write(sb, SB_FREEZE_FS, true);
__sb_start_write(sb, SB_FREEZE_FS);
}
static inline int sb_start_intwrite_trylock(struct super_block *sb)
static inline bool sb_start_intwrite_trylock(struct super_block *sb)
{
return __sb_start_write(sb, SB_FREEZE_FS, false);
return __sb_start_write_trylock(sb, SB_FREEZE_FS);
}
@ -2756,14 +2757,14 @@ static inline void file_start_write(struct file *file)
{
if (!S_ISREG(file_inode(file)->i_mode))
return;
__sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, true);
sb_start_write(file_inode(file)->i_sb);
}
static inline bool file_start_write_trylock(struct file *file)
{
if (!S_ISREG(file_inode(file)->i_mode))
return true;
return __sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, false);
return sb_start_write_trylock(file_inode(file)->i_sb);
}
static inline void file_end_write(struct file *file)