This is an alternate solution to the deadlock problem I mentioned in
my previous patch.
On Tue, Sep 24, 2013 at 3:49 PM, Russ Knize <rknize@xxxxxxxxx> wrote:
> From: Russ Knize <Russ.Knize@xxxxxxxxxxxx>
>
> f2fs_initxattrs() is called internally from within F2FS and should
> not call functions that are used by VFS handlers. This avoids
> certain deadlocks:
>
> - vfs_create()
> - f2fs_create() <-- takes an fs_lock
> - f2fs_add_link()
> - __f2fs_add_link()
> - init_inode_metadata()
> - f2fs_init_security()
> - security_inode_init_security()
> - f2fs_initxattrs()
> - f2fs_setxattr() <-- also takes an fs_lock
>
> If the caller happens to grab the same fs_lock from the pool in both
> places, they will deadlock. There are also deadlocks involving
> multiple threads and mutexes:
>
> - f2fs_write_begin()
> - f2fs_balance_fs() <-- takes gc_mutex
> - f2fs_gc()
> - write_checkpoint()
> - block_operations()
> - mutex_lock_all() <-- blocks trying to grab all fs_locks
>
> - f2fs_mkdir() <-- takes an fs_lock
> - __f2fs_add_link()
> - f2fs_init_security()
> - security_inode_init_security()
> - f2fs_initxattrs()
> - f2fs_setxattr()
> - f2fs_balance_fs() <-- blocks trying to take gc_mutex
>
> Signed-off-by: Russ Knize <Russ.Knize@xxxxxxxxxxxx>
> ---
> fs/f2fs/xattr.c | 35 +++++++++++++++++++++++++----------
> 1 file changed, 25 insertions(+), 10 deletions(-)
>
> diff --git a/fs/f2fs/xattr.c b/fs/f2fs/xattr.c
> index 1ac8a5f..3d900ea 100644
> --- a/fs/f2fs/xattr.c
> +++ b/fs/f2fs/xattr.c
> @@ -154,6 +154,9 @@ static int f2fs_xattr_advise_set(struct dentry *dentry, const char *name,
> }
>
> #ifdef CONFIG_F2FS_FS_SECURITY
> +static int __f2fs_setxattr(struct inode *inode, int name_index,
> + const char *name, const void *value, size_t value_len,
> + struct page *ipage);
> static int f2fs_initxattrs(struct inode *inode, const struct xattr *xattr_array,
> void *page)
> {
> @@ -161,7 +164,7 @@ static int f2fs_initxattrs(struct inode *inode, const struct xattr *xattr_array,
> int err = 0;
>
> for (xattr = xattr_array; xattr->name != NULL; xattr++) {
> - err = f2fs_setxattr(inode, F2FS_XATTR_INDEX_SECURITY,
> + err = __f2fs_setxattr(inode, F2FS_XATTR_INDEX_SECURITY,
> xattr->name, xattr->value,
> xattr->value_len, (struct page *)page);
> if (err < 0)
> @@ -469,16 +472,15 @@ cleanup:
> return error;
> }
>
> -int f2fs_setxattr(struct inode *inode, int name_index, const char *name,
> - const void *value, size_t value_len, struct page *ipage)
> +static int __f2fs_setxattr(struct inode *inode, int name_index,
> + const char *name, const void *value, size_t value_len,
> + struct page *ipage)
> {
> - struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
> struct f2fs_inode_info *fi = F2FS_I(inode);
> struct f2fs_xattr_entry *here, *last;
> void *base_addr;
> int found, newsize;
> size_t name_len;
> - int ilock;
> __u32 new_hsize;
> int error = -ENOMEM;
>
> @@ -493,10 +495,6 @@ int f2fs_setxattr(struct inode *inode, int name_index, const char *name,
> if (name_len > F2FS_NAME_LEN || value_len > MAX_VALUE_LEN(inode))
> return -ERANGE;
>
> - f2fs_balance_fs(sbi);
> -
> - ilock = mutex_lock_op(sbi);
> -
> base_addr = read_all_xattrs(inode, ipage);
> if (!base_addr)
> goto exit;
> @@ -578,7 +576,24 @@ int f2fs_setxattr(struct inode *inode, int name_index, const char *name,
> else
> update_inode_page(inode);
> exit:
> - mutex_unlock_op(sbi, ilock);
> kzfree(base_addr);
> return error;
> }
> +
> +int f2fs_setxattr(struct inode *inode, int name_index, const char *name,
> + const void *value, size_t value_len, struct page *ipage)
> +{
> + struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
> + int ilock;
> + int err;
> +
> + f2fs_balance_fs(sbi);
> +
> + ilock = mutex_lock_op(sbi);
> +
> + err = __f2fs_setxattr(inode, name_index, name, value, value_len, ipage);
> +
> + mutex_unlock_op(sbi, ilock);
> +
> + return err;
> +}
> --
> 1.7.10.4
>
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