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hostfs: hostfs_file_open: Switch to data locking model

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Instead of serializing hostfs_file_open() we can use
a per inode mutex to protect ->mode.

Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Richard Weinberger 2015-02-27 22:55:20 +01:00
parent bc465aa9d0
commit 69886e676e
1 changed files with 7 additions and 6 deletions
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13
fs/hostfs/hostfs_kern.c
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@ -24,6 +24,7 @@ struct hostfs_inode_info {
int fd;
fmode_t mode;
struct inode vfs_inode;
struct mutex open_mutex;
};
static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode)
@ -225,6 +226,7 @@ static struct inode *hostfs_alloc_inode(struct super_block *sb)
hi->fd = -1;
hi->mode = 0;
inode_init_once(&hi->vfs_inode);
mutex_init(&hi->open_mutex);
return &hi->vfs_inode;
}
@ -295,7 +297,6 @@ static int hostfs_readdir(struct file *file, struct dir_context *ctx)
static int hostfs_file_open(struct inode *ino, struct file *file)
{
static DEFINE_MUTEX(open_mutex);
char *name;
fmode_t mode = 0;
int err;
@ -324,15 +325,15 @@ static int hostfs_file_open(struct inode *ino, struct file *file)
if (fd < 0)
return fd;
mutex_lock(&open_mutex);
mutex_lock(&HOSTFS_I(ino)->open_mutex);
/* somebody else had handled it first? */
if ((mode & HOSTFS_I(ino)->mode) == mode) {
mutex_unlock(&open_mutex);
mutex_unlock(&HOSTFS_I(ino)->open_mutex);
return 0;
}
if ((mode | HOSTFS_I(ino)->mode) != mode) {
mode |= HOSTFS_I(ino)->mode;
mutex_unlock(&open_mutex);
mutex_unlock(&HOSTFS_I(ino)->open_mutex);
close_file(&fd);
goto retry;
}
@ -342,12 +343,12 @@ static int hostfs_file_open(struct inode *ino, struct file *file)
err = replace_file(fd, HOSTFS_I(ino)->fd);
close_file(&fd);
if (err < 0) {
mutex_unlock(&open_mutex);
mutex_unlock(&HOSTFS_I(ino)->open_mutex);
return err;
}
}
HOSTFS_I(ino)->mode = mode;
mutex_unlock(&open_mutex);
mutex_unlock(&HOSTFS_I(ino)->open_mutex);
return 0;
}