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mm: tiny-shmem fix lock ordering: mmap_sem vs i_mutex 

tiny-shmem calls do_truncate in shmem_file_setup.  do_truncate takes
i_mutex, and shmem_file_setup is called with mmap_sem held.  However
i_mutex nests outside mmap_sem.

Copy the code in shmem.c to avoid this problem.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Reported-and-tested-by: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Nick Piggin 2008-09-22 13:57:50 -07:00 committed by Linus Torvalds
parent 2d4c826677
commit db203d53d4
1 changed files with 9 additions and 15 deletions
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24
mm/tiny-shmem.c
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@ -65,31 +65,25 @@ struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
if (!dentry)
goto put_memory;
error = -ENOSPC;
inode = ramfs_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
if (!inode)
goto put_dentry;
d_instantiate(dentry, inode);
error = -ENFILE;
file = alloc_file(shm_mnt, dentry, FMODE_WRITE | FMODE_READ,
&ramfs_file_operations);
file = get_empty_filp();
if (!file)
goto put_dentry;
inode->i_nlink = 0; /* It is unlinked */
/* notify everyone as to the change of file size */
error = do_truncate(dentry, size, 0, file);
if (error < 0)
error = -ENOSPC;
inode = ramfs_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
if (!inode)
goto close_file;
d_instantiate(dentry, inode);
inode->i_size = size;
inode->i_nlink = 0; /* It is unlinked */
init_file(file, shm_mnt, dentry, FMODE_WRITE | FMODE_READ,
&ramfs_file_operations);
return file;
close_file:
put_filp(file);
return ERR_PTR(error);
put_dentry:
dput(dentry);
put_memory: