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authorChristoph Hellwig <hch@lst.de>2018-01-09 15:29:24 +0100
committerChristoph Hellwig <hch@lst.de>2018-05-26 09:16:44 +0200
commit3deb642f0de4c14f37437dd247f9c77839f043f8 (patch)
tree56f6867ac66e6fa881295a6c9af52349471374e4 /Documentation/filesystems/Locking
parent9965ed174e7d38896e5d2582159d8ef31ecd4cb5 (diff)
downloadlinux-3deb642f0de4c14f37437dd247f9c77839f043f8.tar.bz2
fs: introduce new ->get_poll_head and ->poll_mask methods
->get_poll_head returns the waitqueue that the poll operation is going to sleep on. Note that this means we can only use a single waitqueue for the poll, unlike some current drivers that use two waitqueues for different events. But now that we have keyed wakeups and heavily use those for poll there aren't that many good reason left to keep the multiple waitqueues, and if there are any ->poll is still around, the driver just won't support aio poll. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Diffstat (limited to 'Documentation/filesystems/Locking')
-rw-r--r--Documentation/filesystems/Locking7
1 files changed, 6 insertions, 1 deletions
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 220bba28f72b..6d227f9d7bd9 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -440,6 +440,8 @@ prototypes:
ssize_t (*write_iter) (struct kiocb *, struct iov_iter *);
int (*iterate) (struct file *, struct dir_context *);
__poll_t (*poll) (struct file *, struct poll_table_struct *);
+ struct wait_queue_head * (*get_poll_head)(struct file *, __poll_t);
+ __poll_t (*poll_mask) (struct file *, __poll_t);
long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
int (*mmap) (struct file *, struct vm_area_struct *);
@@ -470,7 +472,7 @@ prototypes:
};
locking rules:
- All may block.
+ All except for ->poll_mask may block.
->llseek() locking has moved from llseek to the individual llseek
implementations. If your fs is not using generic_file_llseek, you
@@ -498,6 +500,9 @@ in sys_read() and friends.
the lease within the individual filesystem to record the result of the
operation
+->poll_mask can be called with or without the waitqueue lock for the waitqueue
+returned from ->get_poll_head.
+
--------------------------- dquot_operations -------------------------------
prototypes:
int (*write_dquot) (struct dquot *);