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xfs: reduce ilock hold times in xfs_file_aio_write_checks 

We do not need the ilock for generic_write_checks and the i_size_read,
which are protected by i_mutex and/or iolock, so reduce the ilock
critical section to just the call to xfs_zero_eof.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
This commit is contained in:
Christoph Hellwig 2012-03-27 10:34:47 -04:00 committed by Ben Myers
parent b4d05e3019
commit 467f78992a
1 changed files with 9 additions and 14 deletions
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23
fs/xfs/xfs_file.c
View File

@ -593,35 +593,31 @@ xfs_file_aio_write_checks(
struct xfs_inode *ip = XFS_I(inode);
int error = 0;
xfs_rw_ilock(ip, XFS_ILOCK_EXCL);
restart:
error = generic_write_checks(file, pos, count, S_ISBLK(inode->i_mode));
if (error) {
xfs_rw_iunlock(ip, XFS_ILOCK_EXCL);
if (error)
return error;
}
/*
* If the offset is beyond the size of the file, we need to zero any
* blocks that fall between the existing EOF and the start of this
* write. If zeroing is needed and we are currently holding the
* iolock shared, we need to update it to exclusive which involves
* dropping all locks and relocking to maintain correct locking order.
* If we do this, restart the function to ensure all checks and values
* are still valid.
* iolock shared, we need to update it to exclusive which implies
* having to redo all checks before.
*/
if (*pos > i_size_read(inode)) {
if (*iolock == XFS_IOLOCK_SHARED) {
xfs_rw_iunlock(ip, XFS_ILOCK_EXCL | *iolock);
xfs_rw_iunlock(ip, *iolock);
*iolock = XFS_IOLOCK_EXCL;
xfs_rw_ilock(ip, XFS_ILOCK_EXCL | *iolock);
xfs_rw_ilock(ip, *iolock);
goto restart;
}
xfs_rw_ilock(ip, XFS_ILOCK_EXCL);
error = -xfs_zero_eof(ip, *pos, i_size_read(inode));
xfs_rw_iunlock(ip, XFS_ILOCK_EXCL);
if (error)
return error;
}
xfs_rw_iunlock(ip, XFS_ILOCK_EXCL);
if (error)
return error;
/*
* Updating the timestamps will grab the ilock again from
@ -638,7 +634,6 @@ xfs_file_aio_write_checks(
* people from modifying setuid and setgid binaries.
*/
return file_remove_suid(file);
}
/*