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vfs: fix freeze protection in mnt_want_write_file() for overlayfs

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The underlying real file used by overlayfs still contains the overlay path.
This results in mnt_want_write_file() calls by the filesystem getting
freeze protection on the wrong inode (the overlayfs one instead of the real
one).

Fix by using file_inode(file)->i_sb instead of file->f_path.mnt->mnt_sb.

Reported-by: Amir Goldstein <amir73il@gmail.com> 
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Miklos Szeredi 2018-07-18 15:44:43 +02:00
parent 6742cee043
commit a6795a5859
1 changed files with 4 additions and 3 deletions
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7
fs/namespace.c
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@ -441,10 +441,10 @@ int mnt_want_write_file(struct file *file)
{ {
int ret; int ret;
sb_start_write(file->f_path.mnt->mnt_sb); sb_start_write(file_inode(file)->i_sb);
ret = __mnt_want_write_file(file); ret = __mnt_want_write_file(file);
if (ret) if (ret)
sb_end_write(file->f_path.mnt->mnt_sb); sb_end_write(file_inode(file)->i_sb);
return ret; return ret;
} }
EXPORT_SYMBOL_GPL(mnt_want_write_file); EXPORT_SYMBOL_GPL(mnt_want_write_file);
@ -486,7 +486,8 @@ void __mnt_drop_write_file(struct file *file)
void mnt_drop_write_file(struct file *file) void mnt_drop_write_file(struct file *file)
{ {
mnt_drop_write(file->f_path.mnt); __mnt_drop_write_file(file);
sb_end_write(file_inode(file)->i_sb);
} }
EXPORT_SYMBOL(mnt_drop_write_file); EXPORT_SYMBOL(mnt_drop_write_file);