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Commit 7e325d3a authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Al Viro
Browse files

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




locking rules:

locking rules:

	All may block.

	All may block.

			BKL	s_lock	s_umount

	None have BKL

alloc_inode:		no	no	no

			s_umount

destroy_inode:		no

alloc_inode:

dirty_inode:		no				(must not sleep)

destroy_inode:

write_inode:		no

dirty_inode:				(must not sleep)

drop_inode:		no				!!!inode_lock!!!

write_inode:

delete_inode:		no

drop_inode:				!!!inode_lock!!!

put_super:		yes	yes	no

delete_inode:

write_super:		no	yes	read

put_super:		write

sync_fs:		no	no	read

write_super:		read

freeze_fs:		?

sync_fs:		read

unfreeze_fs:		?

freeze_fs:		read

statfs:			no	no	no

unfreeze_fs:		read

remount_fs:		yes	yes	maybe		(see below)

statfs:			no

clear_inode:		no

remount_fs:		maybe		(see below)

umount_begin:		yes	no	no

clear_inode:

show_options:		no				(vfsmount->sem)

umount_begin:		no

quota_read:		no	no	no		(see below)

show_options:		no		(namespace_sem)

quota_write:		no	no	no		(see below)

quota_read:		no		(see below)



quota_write:		no		(see below)

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



->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.

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

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

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

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

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