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kill-the-bkl/reiserfs: don't hold the write recursively in reiserfs_lookup()

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The write lock can be acquired recursively in reiserfs_lookup(). But we may
want to *really* release the lock before possible rescheduling from a
reiserfs_lookup() callee.

Hence we want to only acquire the lock once (ie: not recursively).

[ Impact: prevent from possible false unreleased write lock on sleeping ]

Cc: Jeff Mahoney <jeffm@suse.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
This commit is contained in:
Frederic Weisbecker 2009-05-08 01:05:06 +02:00
parent 26931309a4
commit b1c839bb2d
1 changed files with 10 additions and 3 deletions
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13
fs/reiserfs/namei.c
View file

@ -324,6 +324,7 @@ static struct dentry *reiserfs_lookup(struct inode *dir, struct dentry *dentry,
struct nameidata *nd)
{
int retval;
int lock_depth;
struct inode *inode = NULL;
struct reiserfs_dir_entry de;
INITIALIZE_PATH(path_to_entry);
@ -331,7 +332,13 @@ static struct dentry *reiserfs_lookup(struct inode *dir, struct dentry *dentry,
if (REISERFS_MAX_NAME(dir->i_sb->s_blocksize) < dentry->d_name.len)
return ERR_PTR(-ENAMETOOLONG);
reiserfs_write_lock(dir->i_sb);
/*
* Might be called with or without the write lock, must be careful
* to not recursively hold it in case we want to release the lock
* before rescheduling.
*/
lock_depth = reiserfs_write_lock_once(dir->i_sb);
de.de_gen_number_bit_string = NULL;
retval =
reiserfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len,
@ -341,7 +348,7 @@ static struct dentry *reiserfs_lookup(struct inode *dir, struct dentry *dentry,
inode = reiserfs_iget(dir->i_sb,
(struct cpu_key *)&(de.de_dir_id));
if (!inode || IS_ERR(inode)) {
reiserfs_write_unlock(dir->i_sb);
reiserfs_write_unlock_once(dir->i_sb, lock_depth);
return ERR_PTR(-EACCES);
}
@ -350,7 +357,7 @@ static struct dentry *reiserfs_lookup(struct inode *dir, struct dentry *dentry,
if (IS_PRIVATE(dir))
inode->i_flags |= S_PRIVATE;
}
reiserfs_write_unlock(dir->i_sb);
reiserfs_write_unlock_once(dir->i_sb, lock_depth);
if (retval == IO_ERROR) {
return ERR_PTR(-EIO);
}