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Commit 7e325d3a authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Al Viro
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update Documentation/filesystems/Locking 



The rules for locking in many superblock operations has changed
significantly, so update the documentation for it.  Also correct some
older updates and ommissions.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent f6cc746b

Documentation/filesystems/Locking

+22 −21
Original line number Diff line number Diff line
@@ -109,27 +109,28 @@ prototypes: 


locking rules:

	All may block.

			BKL	s_lock	s_umount

alloc_inode:		no	no	no

destroy_inode:		no

dirty_inode:		no				(must not sleep)

write_inode:		no

drop_inode:		no				!!!inode_lock!!!

delete_inode:		no

put_super:		yes	yes	no

write_super:		no	yes	read

sync_fs:		no	no	read

freeze_fs:		?

unfreeze_fs:		?

statfs:			no	no	no

remount_fs:		yes	yes	maybe		(see below)

clear_inode:		no

umount_begin:		yes	no	no

show_options:		no				(vfsmount->sem)

quota_read:		no	no	no		(see below)

quota_write:		no	no	no		(see below)



->remount_fs() will have the s_umount lock if it's already mounted.

	None have BKL

			s_umount

alloc_inode:

destroy_inode:

dirty_inode:				(must not sleep)

write_inode:

drop_inode:				!!!inode_lock!!!

delete_inode:

put_super:		write

write_super:		read

sync_fs:		read

freeze_fs:		read

unfreeze_fs:		read

statfs:			no

remount_fs:		maybe		(see below)

clear_inode:

umount_begin:		no

show_options:		no		(namespace_sem)

quota_read:		no		(see below)

quota_write:		no		(see below)



->remount_fs() will have the s_umount exclusive lock if it's already mounted.

When called from get_sb_single, it does NOT have the s_umount lock.

->quota_read() and ->quota_write() functions are both guaranteed to

be the only ones operating on the quota file by the quota code (via