synchronous open count in zfs_close() needs to be decremented

[rohan-puri]

Hi Brian,

A small issue : -

z_sync_count needs to be decremented in zfs_close() if O_SYNC flag is specified.

Bug : -

/* Decrement the synchronous opens in the znode */
if (flag & O_SYNC)
zp->z_sync_cnt = 0;

Probable fix : -

/* Decrement the synchronous opens in the znode */
if (flag & O_SYNC)
atomic_dec_32(&zp->z_sync_cnt);

[behlendorf]

Thanks, for catching this. I'll commit a fix shortly which is exactly what you suggest. Did you just happen to stumble across this in the code or did it cause a problem on your system somehow?

[behlendorf]

Actually, I take it back. This isn't quite so simple, I believe the original code is correct but it could certainly use a comment. Unlike Solaris Linux only calls its close/release callback once after everyone who has the file has closed it. For Solaris it is called per-close. So we really do want to set it to zero since this will not be symmetric with open.

[rohan-puri]

I was going through the code and thats when got to it.
Agree to what you say. Its correct, release is called when the last reference to the file object is closed, hence setting it to zero is correct.