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authorAl Viro <viro@zeniv.linux.org.uk>2010-05-26 15:13:55 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2010-05-27 22:03:07 -0400
commitd7065da038227a4d09a244e6014e0186a6bd21d0 (patch)
tree0b3b30a6ec59aa03e5fb7084eed31f2a5dfc9686 /include
parent176306f59ac7a35369cbba87aff13e14c5916074 (diff)
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 'include')
-rw-r--r--include/linux/file.h1
-rw-r--r--include/linux/fs.h1
2 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/file.h b/include/linux/file.h
index 5555508fd517..b1e12970f617 100644
--- a/include/linux/file.h
+++ b/include/linux/file.h
@@ -11,7 +11,6 @@
struct file;
-extern void __fput(struct file *);
extern void fput(struct file *);
extern void drop_file_write_access(struct file *file);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 85e823adcd4a..3d9ed8302402 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -954,6 +954,7 @@ extern spinlock_t files_lock;
#define file_list_unlock() spin_unlock(&files_lock);
#define get_file(x) atomic_long_inc(&(x)->f_count)
+#define fput_atomic(x) atomic_long_add_unless(&(x)->f_count, -1, 1)
#define file_count(x) atomic_long_read(&(x)->f_count)
#ifdef CONFIG_DEBUG_WRITECOUNT