summaryrefslogtreecommitdiff
path: root/fs/ufs/truncate.c
diff options
context:
space:
mode:
authorAl Viro <viro@zeniv.linux.org.uk>2015-06-17 12:02:56 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2015-07-06 17:39:25 -0400
commit724bb09fdc06d4ff03757b25d6dba9ef1b133e8f (patch)
tree5ef4441867f681e132d820c78948b34c0f0ca1df /fs/ufs/truncate.c
parent4af7b2c080715b9452fdaefb7ada72b4dc79593e (diff)
ufs: don't use lock_ufs() for block pointers tree protection
* 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>
Diffstat (limited to 'fs/ufs/truncate.c')
-rw-r--r--fs/ufs/truncate.c22
1 files changed, 20 insertions, 2 deletions
diff --git a/fs/ufs/truncate.c b/fs/ufs/truncate.c
index 9908a6045d7a..ad34b7f4b499 100644
--- a/fs/ufs/truncate.c
+++ b/fs/ufs/truncate.c
@@ -128,7 +128,9 @@ next1:
tmp = ufs_data_ptr_to_cpu(sb, p);
if (!tmp)
continue;
+ write_seqlock(&ufsi->meta_lock);
ufs_data_ptr_clear(uspi, p);
+ write_sequnlock(&ufsi->meta_lock);
if (free_count == 0) {
frag_to_free = tmp;
@@ -157,7 +159,9 @@ next1:
if (!tmp )
ufs_panic(sb, "ufs_truncate_direct", "internal error");
frag4 = ufs_fragnum (frag4);
+ write_seqlock(&ufsi->meta_lock);
ufs_data_ptr_clear(uspi, p);
+ write_sequnlock(&ufsi->meta_lock);
ufs_free_fragments (inode, tmp, frag4);
mark_inode_dirty(inode);
@@ -199,7 +203,9 @@ static int ufs_trunc_indirect(struct inode *inode, u64 offset, void *p)
return 1;
}
if (!ind_ubh) {
+ write_seqlock(&UFS_I(inode)->meta_lock);
ufs_data_ptr_clear(uspi, p);
+ write_sequnlock(&UFS_I(inode)->meta_lock);
return 0;
}
@@ -210,7 +216,9 @@ static int ufs_trunc_indirect(struct inode *inode, u64 offset, void *p)
if (!tmp)
continue;
+ write_seqlock(&UFS_I(inode)->meta_lock);
ufs_data_ptr_clear(uspi, ind);
+ write_sequnlock(&UFS_I(inode)->meta_lock);
ubh_mark_buffer_dirty(ind_ubh);
if (free_count == 0) {
frag_to_free = tmp;
@@ -235,7 +243,9 @@ static int ufs_trunc_indirect(struct inode *inode, u64 offset, void *p)
break;
if (i >= uspi->s_apb) {
tmp = ufs_data_ptr_to_cpu(sb, p);
+ write_seqlock(&UFS_I(inode)->meta_lock);
ufs_data_ptr_clear(uspi, p);
+ write_sequnlock(&UFS_I(inode)->meta_lock);
ubh_bforget(ind_ubh);
ufs_free_blocks (inode, tmp, uspi->s_fpb);
@@ -278,7 +288,9 @@ static int ufs_trunc_dindirect(struct inode *inode, u64 offset, void *p)
return 1;
}
if (!dind_bh) {
+ write_seqlock(&UFS_I(inode)->meta_lock);
ufs_data_ptr_clear(uspi, p);
+ write_sequnlock(&UFS_I(inode)->meta_lock);
return 0;
}
@@ -297,7 +309,9 @@ static int ufs_trunc_dindirect(struct inode *inode, u64 offset, void *p)
break;
if (i >= uspi->s_apb) {
tmp = ufs_data_ptr_to_cpu(sb, p);
+ write_seqlock(&UFS_I(inode)->meta_lock);
ufs_data_ptr_clear(uspi, p);
+ write_sequnlock(&UFS_I(inode)->meta_lock);
ubh_bforget(dind_bh);
ufs_free_blocks(inode, tmp, uspi->s_fpb);
@@ -339,7 +353,9 @@ static int ufs_trunc_tindirect(struct inode *inode)
return 1;
}
if (!tind_bh) {
+ write_seqlock(&ufsi->meta_lock);
ufs_data_ptr_clear(uspi, p);
+ write_sequnlock(&ufsi->meta_lock);
return 0;
}
@@ -355,7 +371,9 @@ static int ufs_trunc_tindirect(struct inode *inode)
break;
if (i >= uspi->s_apb) {
tmp = ufs_data_ptr_to_cpu(sb, p);
+ write_seqlock(&ufsi->meta_lock);
ufs_data_ptr_clear(uspi, p);
+ write_sequnlock(&ufsi->meta_lock);
ubh_bforget(tind_bh);
ufs_free_blocks(inode, tmp, uspi->s_fpb);
@@ -447,7 +465,7 @@ static void __ufs_truncate_blocks(struct inode *inode)
struct ufs_sb_private_info *uspi = UFS_SB(sb)->s_uspi;
int retry;
- lock_ufs(sb);
+ mutex_lock(&ufsi->truncate_mutex);
while (1) {
retry = ufs_trunc_direct(inode);
retry |= ufs_trunc_indirect(inode, UFS_IND_BLOCK,
@@ -465,7 +483,7 @@ static void __ufs_truncate_blocks(struct inode *inode)
}
ufsi->i_lastfrag = DIRECT_FRAGMENT;
- unlock_ufs(sb);
+ mutex_unlock(&ufsi->truncate_mutex);
}
int ufs_truncate(struct inode *inode, loff_t size)