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[Qemu-block] [PATCH v2 0/2] blockdev: avoid acquiring AioContext lock tw

From: Sergio Lopez
Subject: [Qemu-block] [PATCH v2 0/2] blockdev: avoid acquiring AioContext lock twice at do_drive_backup()
Date: Fri, 13 Sep 2019 17:25:06 +0200

do_drive_backup() acquires the AioContext lock of the corresponding
BlockDriverState. This is not a problem when it's called from
qmp_drive_backup(), but drive_backup_prepare() also acquires the lock
before calling it.

Additionally, Max Reitz pointed out that bdrv_try_set_aio_context() is
called at do_backup_common() with the new context held, and the old
context not held, while it expects it to be the other way
around. This is also the case for other uses of that function on

This patch series fixes all occurrences of bdrv_try_set_aio_context()
to honor the context requirements. It also changes
drive_backup_prepare() to release the context before calling


 - Honor bdrv_try_set_aio_context() context acquisition requirements
   (thanks Max Reitz).
 - Release the context at drive_backup_prepare() instead of avoiding
   re-acquiring it at do_drive_baclup(). (thanks Max Reitz)
 - Convert a single patch into a two-patch series.

Sergio Lopez (2):
  blockdev: release the AioContext at drive_backup_prepare
  blockdev: honor bdrv_try_set_aio_context() context requirements

 blockdev.c | 127 ++++++++++++++++++++++++++++++++---------------------
 1 file changed, 76 insertions(+), 51 deletions(-)


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