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Message-ID: <alpine.DEB.2.00.1105082024500.7013@artax.karlin.mff.cuni.cz>
Date: Sun, 8 May 2011 20:42:54 +0200 (CEST)
From: Mikulas Patocka <mikulas@...ax.karlin.mff.cuni.cz>
To: Linus Torvalds <torvalds@...ux-foundation.org>
cc: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: [PATCH 2/14] HPFS: Introduce a global mutex and lock it on every
callback from VFS.
Introduce a global mutex and lock it on every callback from VFS.
Performance doesn't matter, reviewing the whole code for locking correctness
would be too complicated, so simply lock it all.
Signed-off-by: Mikulas Patocka <mikulas@...ax.karlin.mff.cuni.cz>
---
fs/hpfs/buffer.c | 8 ++++++++
fs/hpfs/file.c | 27 +++++++++++++++++++--------
fs/hpfs/hpfs_fn.h | 24 +++++++++++++++---------
fs/hpfs/super.c | 10 +++++++++-
4 files changed, 51 insertions(+), 18 deletions(-)
Index: linux-2.6.39-rc5-fast/fs/hpfs/hpfs_fn.h
===================================================================
--- linux-2.6.39-rc5-fast.orig/fs/hpfs/hpfs_fn.h 2011-05-05 01:01:57.000000000 +0200
+++ linux-2.6.39-rc5-fast/fs/hpfs/hpfs_fn.h 2011-05-05 01:02:43.000000000 +0200
@@ -63,6 +63,7 @@ struct hpfs_inode_info {
};
struct hpfs_sb_info {
+ struct mutex hpfs_mutex; /* global hpfs lock */
ino_t sb_root; /* inode number of root dir */
unsigned sb_fs_size; /* file system size, sectors */
unsigned sb_bitmaps; /* sector number of bitmap list */
@@ -346,21 +347,26 @@ static inline time32_t gmt_to_local(stru
/*
* Locking:
*
- * hpfs_lock() is a leftover from the big kernel lock.
- * Right now, these functions are empty and only left
- * for documentation purposes. The file system no longer
- * works on SMP systems, so the lock is not needed
- * any more.
+ * hpfs_lock() locks the whole filesystem. It must be taken
+ * on any method called by the VFS.
*
- * If someone is interested in making it work again, this
- * would be the place to start by adding a per-superblock
- * mutex and fixing all the bugs and performance issues
- * caused by that.
+ * We don't do any per-file locking anymore, it is hard to
+ * review and HPFS is not performance-sensitive anyway.
*/
static inline void hpfs_lock(struct super_block *s)
{
+ struct hpfs_sb_info *sbi = hpfs_sb(s);
+ mutex_lock(&sbi->hpfs_mutex);
}
static inline void hpfs_unlock(struct super_block *s)
{
+ struct hpfs_sb_info *sbi = hpfs_sb(s);
+ mutex_unlock(&sbi->hpfs_mutex);
+}
+
+static inline void hpfs_lock_assert(struct super_block *s)
+{
+ struct hpfs_sb_info *sbi = hpfs_sb(s);
+ WARN_ON(!mutex_is_locked(&sbi->hpfs_mutex));
}
Index: linux-2.6.39-rc5-fast/fs/hpfs/super.c
===================================================================
--- linux-2.6.39-rc5-fast.orig/fs/hpfs/super.c 2011-05-05 01:02:36.000000000 +0200
+++ linux-2.6.39-rc5-fast/fs/hpfs/super.c 2011-05-05 01:02:43.000000000 +0200
@@ -102,9 +102,12 @@ static void hpfs_put_super(struct super_
{
struct hpfs_sb_info *sbi = hpfs_sb(s);
+ hpfs_lock(s);
+ unmark_dirty(s);
+ hpfs_unlock(s);
+
kfree(sbi->sb_cp_table);
kfree(sbi->sb_bmp_dir);
- unmark_dirty(s);
s->s_fs_info = NULL;
kfree(sbi);
}
@@ -490,6 +493,9 @@ static int hpfs_fill_super(struct super_
sbi->sb_bmp_dir = NULL;
sbi->sb_cp_table = NULL;
+ mutex_init(&sbi->hpfs_mutex);
+ hpfs_lock(s);
+
mutex_init(&sbi->hpfs_creation_de);
uid = current_uid();
@@ -669,6 +675,7 @@ static int hpfs_fill_super(struct super_
root->i_blocks = 5;
hpfs_brelse4(&qbh);
}
+ hpfs_unlock(s);
return 0;
bail4: brelse(bh2);
@@ -676,6 +683,7 @@ bail3: brelse(bh1);
bail2: brelse(bh0);
bail1:
bail0:
+ hpfs_unlock(s);
kfree(sbi->sb_bmp_dir);
kfree(sbi->sb_cp_table);
s->s_fs_info = NULL;
Index: linux-2.6.39-rc5-fast/fs/hpfs/file.c
===================================================================
--- linux-2.6.39-rc5-fast.orig/fs/hpfs/file.c 2011-05-05 01:01:57.000000000 +0200
+++ linux-2.6.39-rc5-fast/fs/hpfs/file.c 2011-05-05 01:02:43.000000000 +0200
@@ -48,38 +48,46 @@ static secno hpfs_bmap(struct inode *ino
static void hpfs_truncate(struct inode *i)
{
if (IS_IMMUTABLE(i)) return /*-EPERM*/;
- hpfs_lock(i->i_sb);
+ hpfs_lock_assert(i->i_sb);
+
hpfs_i(i)->i_n_secs = 0;
i->i_blocks = 1 + ((i->i_size + 511) >> 9);
hpfs_i(i)->mmu_private = i->i_size;
hpfs_truncate_btree(i->i_sb, i->i_ino, 1, ((i->i_size + 511) >> 9));
hpfs_write_inode(i);
hpfs_i(i)->i_n_secs = 0;
- hpfs_unlock(i->i_sb);
}
static int hpfs_get_block(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create)
{
+ int r;
secno s;
+ hpfs_lock(inode->i_sb);
s = hpfs_bmap(inode, iblock);
if (s) {
map_bh(bh_result, inode->i_sb, s);
- return 0;
+ goto ret_0;
}
- if (!create) return 0;
+ if (!create) goto ret_0;
if (iblock<<9 != hpfs_i(inode)->mmu_private) {
BUG();
- return -EIO;
+ r = -EIO;
+ goto ret_r;
}
if ((s = hpfs_add_sector_to_btree(inode->i_sb, inode->i_ino, 1, inode->i_blocks - 1)) == -1) {
hpfs_truncate_btree(inode->i_sb, inode->i_ino, 1, inode->i_blocks - 1);
- return -ENOSPC;
+ r = -ENOSPC;
+ goto ret_r;
}
inode->i_blocks++;
hpfs_i(inode)->mmu_private += 512;
set_buffer_new(bh_result);
map_bh(bh_result, inode->i_sb, s);
- return 0;
+ ret_0:
+ r = 0;
+ ret_r:
+ hpfs_unlock(inode->i_sb);
+ return r;
}
static int hpfs_writepage(struct page *page, struct writeback_control *wbc)
@@ -130,8 +138,11 @@ static ssize_t hpfs_file_write(struct fi
ssize_t retval;
retval = do_sync_write(file, buf, count, ppos);
- if (retval > 0)
+ if (retval > 0) {
+ hpfs_lock(file->f_path.dentry->d_sb);
hpfs_i(file->f_path.dentry->d_inode)->i_dirty = 1;
+ hpfs_unlock(file->f_path.dentry->d_sb);
+ }
return retval;
}
Index: linux-2.6.39-rc5-fast/fs/hpfs/buffer.c
===================================================================
--- linux-2.6.39-rc5-fast.orig/fs/hpfs/buffer.c 2011-05-05 01:01:57.000000000 +0200
+++ linux-2.6.39-rc5-fast/fs/hpfs/buffer.c 2011-05-05 01:02:43.000000000 +0200
@@ -32,6 +32,8 @@ void *hpfs_map_sector(struct super_block
{
struct buffer_head *bh;
+ hpfs_lock_assert(s);
+
cond_resched();
*bhp = bh = sb_bread(s, secno);
@@ -50,6 +52,8 @@ void *hpfs_get_sector(struct super_block
struct buffer_head *bh;
/*return hpfs_map_sector(s, secno, bhp, 0);*/
+ hpfs_lock_assert(s);
+
cond_resched();
if ((*bhp = bh = sb_getblk(s, secno)) != NULL) {
@@ -70,6 +74,8 @@ void *hpfs_map_4sectors(struct super_blo
struct buffer_head *bh;
char *data;
+ hpfs_lock_assert(s);
+
cond_resched();
if (secno & 3) {
@@ -125,6 +131,8 @@ void *hpfs_get_4sectors(struct super_blo
{
cond_resched();
+ hpfs_lock_assert(s);
+
if (secno & 3) {
printk("HPFS: hpfs_get_4sectors: unaligned read\n");
return NULL;
--
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