forked from luck/tmp_suning_uos_patched
aa9714d0e3
Earlier there was no shared lock in DIO read path. But this patch (16c54688592ce: ext4: Allow parallel DIO reads) simplified some of the locking mechanism while still allowing for parallel DIO reads by adding shared lock in inode DIO read path. But this created problem with mixed read/write workload. It is due to the fact that in DIO path, we first start with exclusive lock and only when we determine that it is a ovewrite IO, we downgrade the lock. This causes the problem, since we still have shared locking in DIO reads. So, this patch tries to fix this issue by starting with shared lock and then switching to exclusive lock only when required based on ext4_dio_write_checks(). Other than that, it also simplifies below cases:- 1. Simplified ext4_unaligned_aio API to ext4_unaligned_io. Previous API was abused in the sense that it was not really checking for AIO anywhere also it used to check for extending writes. So this API was renamed and simplified to ext4_unaligned_io() which actully only checks if the IO is really unaligned. Now, in case of unaligned direct IO, iomap_dio_rw needs to do zeroing of partial block and that will require serialization against other direct IOs in the same block. So we take a exclusive inode lock for any unaligned DIO. In case of AIO we also need to wait for any outstanding IOs to complete so that conversion from unwritten to written is completed before anyone try to map the overlapping block. Hence we take exclusive inode lock and also wait for inode_dio_wait() for unaligned DIO case. Please note since we are anyway taking an exclusive lock in unaligned IO, inode_dio_wait() becomes a no-op in case of non-AIO DIO. 2. Added ext4_extending_io(). This checks if the IO is extending the file. 3. Added ext4_dio_write_checks(). In this we start with shared inode lock and only switch to exclusive lock if required. So in most cases with aligned, non-extending, dioread_nolock & overwrites, it tries to write with a shared lock. If not, then we restart the operation in ext4_dio_write_checks(), after acquiring exclusive lock. Reviewed-by: Jan Kara <jack@suse.cz> Tested-by: Joseph Qi <joseph.qi@linux.alibaba.com> Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com> Link: https://lore.kernel.org/r/20191212055557.11151-3-riteshh@linux.ibm.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> |
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| .. | ||
| acl.c | ||
| acl.h | ||
| balloc.c | ||
| bitmap.c | ||
| block_validity.c | ||
| dir.c | ||
| ext4_extents.h | ||
| ext4_jbd2.c | ||
| ext4_jbd2.h | ||
| ext4.h | ||
| extents_status.c | ||
| extents_status.h | ||
| extents.c | ||
| file.c | ||
| fsmap.c | ||
| fsmap.h | ||
| fsync.c | ||
| hash.c | ||
| ialloc.c | ||
| indirect.c | ||
| inline.c | ||
| inode-test.c | ||
| inode.c | ||
| ioctl.c | ||
| Kconfig | ||
| Makefile | ||
| mballoc.c | ||
| mballoc.h | ||
| migrate.c | ||
| mmp.c | ||
| move_extent.c | ||
| namei.c | ||
| page-io.c | ||
| readpage.c | ||
| resize.c | ||
| super.c | ||
| symlink.c | ||
| sysfs.c | ||
| truncate.h | ||
| verity.c | ||
| xattr_security.c | ||
| xattr_trusted.c | ||
| xattr_user.c | ||
| xattr.c | ||
| xattr.h | ||