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author | Al Viro <viro@zeniv.linux.org.uk> | 2010-05-26 15:13:55 -0400 |
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committer | Al Viro <viro@zeniv.linux.org.uk> | 2010-05-27 22:03:07 -0400 |
commit | d7065da038227a4d09a244e6014e0186a6bd21d0 (patch) | |
tree | 0b3b30a6ec59aa03e5fb7084eed31f2a5dfc9686 /fs/aio.c | |
parent | 176306f59ac7a35369cbba87aff13e14c5916074 (diff) | |
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get rid of the magic around f_count in aio
__aio_put_req() plays sick games with file refcount. What
it wants is fput() from atomic context; it's almost always
done with f_count > 1, so they only have to deal with delayed
work in rare cases when their reference happens to be the
last one. Current code decrements f_count and if it hasn't
hit 0, everything is fine. Otherwise it keeps a pointer
to struct file (with zero f_count!) around and has delayed
work do __fput() on it.
Better way to do it: use atomic_long_add_unless( , -1, 1)
instead of !atomic_long_dec_and_test(). IOW, decrement it
only if it's not the last reference, leave refcount alone
if it was. And use normal fput() in delayed work.
I've made that atomic_long_add_unless call a new helper -
fput_atomic(). Drops a reference to file if it's safe to
do in atomic (i.e. if that's not the last one), tells if
it had been able to do that. aio.c converted to it, __fput()
use is gone. req->ki_file *always* contributes to refcount
now. And __fput() became static.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/aio.c')
-rw-r--r-- | fs/aio.c | 6 |
1 files changed, 3 insertions, 3 deletions
@@ -527,7 +527,7 @@ static void aio_fput_routine(struct work_struct *data) /* Complete the fput(s) */ if (req->ki_filp != NULL) - __fput(req->ki_filp); + fput(req->ki_filp); /* Link the iocb into the context's free list */ spin_lock_irq(&ctx->ctx_lock); @@ -560,11 +560,11 @@ static int __aio_put_req(struct kioctx *ctx, struct kiocb *req) /* * Try to optimize the aio and eventfd file* puts, by avoiding to - * schedule work in case it is not __fput() time. In normal cases, + * schedule work in case it is not final fput() time. In normal cases, * we would not be holding the last reference to the file*, so * this function will be executed w/out any aio kthread wakeup. */ - if (unlikely(atomic_long_dec_and_test(&req->ki_filp->f_count))) { + if (unlikely(!fput_atomic(req->ki_filp))) { get_ioctx(ctx); spin_lock(&fput_lock); list_add(&req->ki_list, &fput_head); |