提交 7dd29d8d 编写于 作者: M Mikulas Patocka 提交者: Linus Torvalds

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: NMikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
上级 637b424b
......@@ -32,6 +32,8 @@ void *hpfs_map_sector(struct super_block *s, unsigned secno, struct buffer_head
{
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 *s, unsigned secno, struct buffer_head
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_block *s, unsigned secno, struct quad_buffe
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_block *s, unsigned secno,
{
cond_resched();
hpfs_lock_assert(s);
if (secno & 3) {
printk("HPFS: hpfs_get_4sectors: unaligned read\n");
return NULL;
......
......@@ -48,38 +48,46 @@ static secno hpfs_bmap(struct inode *inode, unsigned file_secno)
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 file *file, const char __user *buf,
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;
}
......
......@@ -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(struct super_block *s, time_t t)
/*
* 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));
}
......@@ -102,9 +102,12 @@ static void hpfs_put_super(struct super_block *s)
{
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_block *s, void *options, int silent)
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_block *s, void *options, int silent)
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;
......
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