Messages in this thread Patch in this message | | | Subject | [PATCH 21/27] r-o-bind-mounts-make-access-use-mnt-check | From | Dave Hansen <> | Date | Thu, 01 Nov 2007 16:08:54 -0700 |
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It is OK to let access() go without using a mnt_want/drop_write() pair because it doesn't actually do writes to the filesystem, and it is inherently racy anyway. This is a rare case when it is OK to use __mnt_is_readonly() directly.
Acked-by: Christoph Hellwig <hch@infradead.org> Signed-off-by: Dave Hansen <haveblue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> ---
linux-2.6.git-dave/fs/open.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)
diff -puN fs/open.c~r-o-bind-mounts-make-access-use-mnt-check fs/open.c --- linux-2.6.git/fs/open.c~r-o-bind-mounts-make-access-use-mnt-check 2007-11-01 14:46:18.000000000 -0700 +++ linux-2.6.git-dave/fs/open.c 2007-11-01 14:46:18.000000000 -0700 @@ -459,8 +459,17 @@ asmlinkage long sys_faccessat(int dfd, c if(res || !(mode & S_IWOTH) || special_file(nd.dentry->d_inode->i_mode)) goto out_path_release; - - if(IS_RDONLY(nd.dentry->d_inode)) + /* + * This is a rare case where using __mnt_is_readonly() + * is OK without a mnt_want/drop_write() pair. Since + * no actual write to the fs is performed here, we do + * not need to telegraph to that to anyone. + * + * By doing this, we accept that this access is + * inherently racy and know that the fs may change + * state before we even see this result. + */ + if (__mnt_is_readonly(nd.mnt)) res = -EROFS; out_path_release: _ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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