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724bb09fdc
* stores to block pointers are under per-inode seqlock (meta_lock) and mutex (truncate_mutex) * fetches of block pointers are either under truncate_mutex, or wrapped into seqretry loop on meta_lock * all changes of ->i_size are under truncate_mutex and i_mutex * all changes of ->i_lastfrag are under truncate_mutex It's similar to what ext2 is doing; the main difference is that unlike ext2 we can't rely upon the atomicity of stores into block pointers - on UFS2 they are 64bit. So we can't cut the corner when switching a pointer from NULL to non-NULL as we could in ext2_splice_branch() and need to use meta_lock on all modifications. We use seqlock where ext2 uses rwlock; ext2 could probably also benefit from such change... Another non-trivial difference is that with UFS we *cannot* have reader grab truncate_mutex in case of race - it has to keep retrying. That might be possible to change, but not until we lift tail unpacking several levels up in call chain. After that commit we do *NOT* hold fs-wide serialization on accesses to block pointers anymore. Moreover, lock_ufs() can become a normal mutex now - it's only used on statfs, remount and sync_fs and none of those uses are recursive. As the matter of fact, *now* it can be collapsed with ->s_lock, and be eventually replaced with saner per-cylinder-group spinlocks, but that's a separate story. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> |
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| .. | ||
| balloc.c | ||
| cylinder.c | ||
| dir.c | ||
| file.c | ||
| ialloc.c | ||
| inode.c | ||
| Kconfig | ||
| Makefile | ||
| namei.c | ||
| super.c | ||
| swab.h | ||
| symlink.c | ||
| truncate.c | ||
| ufs_fs.h | ||
| ufs.h | ||
| util.c | ||
| util.h | ||