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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
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')
-rw-r--r--fs/ufs/balloc.c4
-rw-r--r--fs/ufs/inode.c138
-rw-r--r--fs/ufs/super.c2
-rw-r--r--fs/ufs/truncate.c22
-rw-r--r--fs/ufs/ufs.h2
5 files changed, 121 insertions, 47 deletions
diff --git a/fs/ufs/balloc.c b/fs/ufs/balloc.c
index a7106eda5024..fb8b54eb77c5 100644
--- a/fs/ufs/balloc.c
+++ b/fs/ufs/balloc.c
@@ -417,7 +417,9 @@ u64 ufs_new_fragments(struct inode *inode, void *p, u64 fragment,
if (oldcount == 0) {
result = ufs_alloc_fragments (inode, cgno, goal, count, err);
if (result) {
+ write_seqlock(&UFS_I(inode)->meta_lock);
ufs_cpu_to_data_ptr(sb, p, result);
+ write_sequnlock(&UFS_I(inode)->meta_lock);
*err = 0;
UFS_I(inode)->i_lastfrag =
max(UFS_I(inode)->i_lastfrag, fragment + count);
@@ -473,7 +475,9 @@ u64 ufs_new_fragments(struct inode *inode, void *p, u64 fragment,
ufs_change_blocknr(inode, fragment - oldcount, oldcount,
uspi->s_sbbase + tmp,
uspi->s_sbbase + result, locked_page);
+ write_seqlock(&UFS_I(inode)->meta_lock);
ufs_cpu_to_data_ptr(sb, p, result);
+ write_sequnlock(&UFS_I(inode)->meta_lock);
*err = 0;
UFS_I(inode)->i_lastfrag = max(UFS_I(inode)->i_lastfrag,
fragment + count);
diff --git a/fs/ufs/inode.c b/fs/ufs/inode.c
index a4fc3adfdc4c..100f93c6b309 100644
--- a/fs/ufs/inode.c
+++ b/fs/ufs/inode.c
@@ -41,8 +41,6 @@
#include "swab.h"
#include "util.h"
-static u64 ufs_frag_map(struct inode *inode, sector_t frag, bool needs_lock);
-
static int ufs_block_to_path(struct inode *inode, sector_t i_block, sector_t offsets[4])
{
struct ufs_sb_private_info *uspi = UFS_SB(inode->i_sb)->s_uspi;
@@ -75,12 +73,53 @@ static int ufs_block_to_path(struct inode *inode, sector_t i_block, sector_t off
return n;
}
+typedef struct {
+ void *p;
+ union {
+ __fs32 key32;
+ __fs64 key64;
+ };
+ struct buffer_head *bh;
+} Indirect;
+
+static inline int grow_chain32(struct ufs_inode_info *ufsi,
+ struct buffer_head *bh, __fs32 *v,
+ Indirect *from, Indirect *to)
+{
+ Indirect *p;
+ unsigned seq;
+ to->bh = bh;
+ do {
+ seq = read_seqbegin(&ufsi->meta_lock);
+ to->key32 = *(__fs32 *)(to->p = v);
+ for (p = from; p <= to && p->key32 == *(__fs32 *)p->p; p++)
+ ;
+ } while (read_seqretry(&ufsi->meta_lock, seq));
+ return (p > to);
+}
+
+static inline int grow_chain64(struct ufs_inode_info *ufsi,
+ struct buffer_head *bh, __fs64 *v,
+ Indirect *from, Indirect *to)
+{
+ Indirect *p;
+ unsigned seq;
+ to->bh = bh;
+ do {
+ seq = read_seqbegin(&ufsi->meta_lock);
+ to->key64 = *(__fs64 *)(to->p = v);
+ for (p = from; p <= to && p->key64 == *(__fs64 *)p->p; p++)
+ ;
+ } while (read_seqretry(&ufsi->meta_lock, seq));
+ return (p > to);
+}
+
/*
* Returns the location of the fragment from
* the beginning of the filesystem.
*/
-static u64 ufs_frag_map(struct inode *inode, sector_t frag, bool needs_lock)
+static u64 ufs_frag_map(struct inode *inode, sector_t frag)
{
struct ufs_inode_info *ufsi = UFS_I(inode);
struct super_block *sb = inode->i_sb;
@@ -88,12 +127,10 @@ static u64 ufs_frag_map(struct inode *inode, sector_t frag, bool needs_lock)
u64 mask = (u64) uspi->s_apbmask>>uspi->s_fpbshift;
int shift = uspi->s_apbshift-uspi->s_fpbshift;
sector_t offsets[4], *p;
+ Indirect chain[4], *q = chain;
int depth = ufs_block_to_path(inode, frag >> uspi->s_fpbshift, offsets);
- u64 ret = 0L;
- __fs32 block;
- __fs64 u2_block = 0L;
unsigned flags = UFS_SB(sb)->s_flags;
- u64 temp = 0L;
+ u64 res = 0;
UFSD(": frag = %llu depth = %d\n", (unsigned long long)frag, depth);
UFSD(": uspi->s_fpbshift = %d ,uspi->s_apbmask = %x, mask=%llx\n",
@@ -101,59 +138,73 @@ static u64 ufs_frag_map(struct inode *inode, sector_t frag, bool needs_lock)
(unsigned long long)mask);
if (depth == 0)
- return 0;
+ goto no_block;
+again:
p = offsets;
- if (needs_lock)
- lock_ufs(sb);
if ((flags & UFS_TYPE_MASK) == UFS_TYPE_UFS2)
goto ufs2;
- block = ufsi->i_u1.i_data[*p++];
- if (!block)
- goto out;
+ if (!grow_chain32(ufsi, NULL, &ufsi->i_u1.i_data[*p++], chain, q))
+ goto changed;
+ if (!q->key32)
+ goto no_block;
while (--depth) {
+ __fs32 *ptr;
struct buffer_head *bh;
sector_t n = *p++;
- bh = sb_bread(sb, uspi->s_sbbase + fs32_to_cpu(sb, block)+(n>>shift));
+ bh = sb_bread(sb, uspi->s_sbbase +
+ fs32_to_cpu(sb, q->key32) + (n>>shift));
if (!bh)
- goto out;
- block = ((__fs32 *) bh->b_data)[n & mask];
- brelse (bh);
- if (!block)
- goto out;
+ goto no_block;
+ ptr = (__fs32 *)bh->b_data + (n & mask);
+ if (!grow_chain32(ufsi, bh, ptr, chain, ++q))
+ goto changed;
+ if (!q->key32)
+ goto no_block;
}
- ret = (u64) (uspi->s_sbbase + fs32_to_cpu(sb, block) + (frag & uspi->s_fpbmask));
- goto out;
-ufs2:
- u2_block = ufsi->i_u1.u2_i_data[*p++];
- if (!u2_block)
- goto out;
+ res = fs32_to_cpu(sb, q->key32);
+ goto found;
+ufs2:
+ if (!grow_chain64(ufsi, NULL, &ufsi->i_u1.u2_i_data[*p++], chain, q))
+ goto changed;
+ if (!q->key64)
+ goto no_block;
while (--depth) {
+ __fs64 *ptr;
struct buffer_head *bh;
sector_t n = *p++;
-
- temp = (u64)(uspi->s_sbbase) + fs64_to_cpu(sb, u2_block);
- bh = sb_bread(sb, temp +(u64) (n>>shift));
+ bh = sb_bread(sb, uspi->s_sbbase +
+ fs64_to_cpu(sb, q->key64) + (n>>shift));
if (!bh)
- goto out;
- u2_block = ((__fs64 *)bh->b_data)[n & mask];
- brelse(bh);
- if (!u2_block)
- goto out;
+ goto no_block;
+ ptr = (__fs64 *)bh->b_data + (n & mask);
+ if (!grow_chain64(ufsi, bh, ptr, chain, ++q))
+ goto changed;
+ if (!q->key64)
+ goto no_block;
+ }
+ res = fs64_to_cpu(sb, q->key64);
+found:
+ res += uspi->s_sbbase + (frag & uspi->s_fpbmask);
+no_block:
+ while (q > chain) {
+ brelse(q->bh);
+ q--;
}
- temp = (u64)uspi->s_sbbase + fs64_to_cpu(sb, u2_block);
- ret = temp + (u64) (frag & uspi->s_fpbmask);
+ return res;
-out:
- if (needs_lock)
- unlock_ufs(sb);
- return ret;
+changed:
+ while (q > chain) {
+ brelse(q->bh);
+ q--;
+ }
+ goto again;
}
/**
@@ -421,10 +472,9 @@ int ufs_getfrag_block(struct inode *inode, sector_t fragment, struct buffer_head
int ret, err, new;
unsigned long ptr,phys;
u64 phys64 = 0;
- bool needs_lock = (sbi->mutex_owner != current);
if (!create) {
- phys64 = ufs_frag_map(inode, fragment, needs_lock);
+ phys64 = ufs_frag_map(inode, fragment);
UFSD("phys64 = %llu\n", (unsigned long long)phys64);
if (phys64)
map_bh(bh_result, sb, phys64);
@@ -438,8 +488,7 @@ int ufs_getfrag_block(struct inode *inode, sector_t fragment, struct buffer_head
ret = 0;
bh = NULL;
- if (needs_lock)
- lock_ufs(sb);
+ mutex_lock(&UFS_I(inode)->truncate_mutex);
UFSD("ENTER, ino %lu, fragment %llu\n", inode->i_ino, (unsigned long long)fragment);
if (fragment >
@@ -501,8 +550,7 @@ out:
set_buffer_new(bh_result);
map_bh(bh_result, sb, phys);
abort:
- if (needs_lock)
- unlock_ufs(sb);
+ mutex_unlock(&UFS_I(inode)->truncate_mutex);
return err;
diff --git a/fs/ufs/super.c b/fs/ufs/super.c
index 250579a80d90..15cd3338340c 100644
--- a/fs/ufs/super.c
+++ b/fs/ufs/super.c
@@ -1429,6 +1429,8 @@ static struct inode *ufs_alloc_inode(struct super_block *sb)
return NULL;
ei->vfs_inode.i_version = 1;
+ seqlock_init(&ei->meta_lock);
+ mutex_init(&ei->truncate_mutex);
return &ei->vfs_inode;
}
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)
diff --git a/fs/ufs/ufs.h b/fs/ufs/ufs.h
index 43fcab381de1..ea28b73a8b74 100644
--- a/fs/ufs/ufs.h
+++ b/fs/ufs/ufs.h
@@ -46,6 +46,8 @@ struct ufs_inode_info {
__u32 i_oeftflag;
__u16 i_osync;
__u64 i_lastfrag;
+ seqlock_t meta_lock;
+ struct mutex truncate_mutex;
__u32 i_dir_start_lookup;
struct inode vfs_inode;
};