[PATCH] do namei_flags calculation inside open_namei()
My end goal here is to make sure all users of may_open() return filps. This will ensure that we properly release mount write counts which were taken for the filp in may_open(). This patch moves the sys_open flags to namei flags calculation into fs/namei.c. We'll shortly be moving the nameidata_to_filp() calls into namei.c, and this gets the sys_open flags to a place where we can get at them when we need them. Acked-by: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dave Hansen <haveblue@us.ibm.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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parent
3925e6fc1f
commit
d57999e152
2 changed files with 36 additions and 29 deletions
43
fs/namei.c
43
fs/namei.c
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@ -1677,7 +1677,12 @@ int may_open(struct nameidata *nd, int acc_mode, int flag)
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return 0;
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}
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static int open_namei_create(struct nameidata *nd, struct path *path,
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/*
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* Be careful about ever adding any more callers of this
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* function. Its flags must be in the namei format, not
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* what get passed to sys_open().
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*/
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static int __open_namei_create(struct nameidata *nd, struct path *path,
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int flag, int mode)
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{
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int error;
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@ -1695,27 +1700,47 @@ static int open_namei_create(struct nameidata *nd, struct path *path,
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return may_open(nd, 0, flag & ~O_TRUNC);
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}
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/*
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* Note that while the flag value (low two bits) for sys_open means:
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* 00 - read-only
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* 01 - write-only
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* 10 - read-write
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* 11 - special
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* it is changed into
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* 00 - no permissions needed
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* 01 - read-permission
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* 10 - write-permission
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* 11 - read-write
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* for the internal routines (ie open_namei()/follow_link() etc)
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* This is more logical, and also allows the 00 "no perm needed"
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* to be used for symlinks (where the permissions are checked
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* later).
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*
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*/
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static inline int open_to_namei_flags(int flag)
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{
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if ((flag+1) & O_ACCMODE)
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flag++;
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return flag;
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}
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/*
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* open_namei()
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*
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* namei for open - this is in fact almost the whole open-routine.
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*
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* Note that the low bits of "flag" aren't the same as in the open
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* system call - they are 00 - no permissions needed
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* 01 - read permission needed
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* 10 - write permission needed
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* 11 - read/write permissions needed
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* which is a lot more logical, and also allows the "no perm" needed
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* for symlinks (where the permissions are checked later).
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* system call. See open_to_namei_flags().
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* SMP-safe
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*/
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int open_namei(int dfd, const char *pathname, int flag,
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int open_namei(int dfd, const char *pathname, int open_flag,
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int mode, struct nameidata *nd)
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{
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int acc_mode, error;
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struct path path;
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struct dentry *dir;
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int count = 0;
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int flag = open_to_namei_flags(open_flag);
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acc_mode = ACC_MODE(flag);
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@ -1776,7 +1801,7 @@ int open_namei(int dfd, const char *pathname, int flag,
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/* Negative dentry, just create the file */
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if (!path.dentry->d_inode) {
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error = open_namei_create(nd, &path, flag, mode);
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error = __open_namei_create(nd, &path, flag, mode);
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if (error)
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goto exit;
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return 0;
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22
fs/open.c
22
fs/open.c
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@ -796,31 +796,13 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
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return ERR_PTR(error);
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}
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/*
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* Note that while the flag value (low two bits) for sys_open means:
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* 00 - read-only
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* 01 - write-only
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* 10 - read-write
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* 11 - special
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* it is changed into
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* 00 - no permissions needed
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* 01 - read-permission
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* 10 - write-permission
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* 11 - read-write
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* for the internal routines (ie open_namei()/follow_link() etc). 00 is
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* used by symlinks.
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*/
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static struct file *do_filp_open(int dfd, const char *filename, int flags,
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int mode)
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{
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int namei_flags, error;
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int error;
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struct nameidata nd;
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namei_flags = flags;
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if ((namei_flags+1) & O_ACCMODE)
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namei_flags++;
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error = open_namei(dfd, filename, namei_flags, mode, &nd);
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error = open_namei(dfd, filename, flags, mode, &nd);
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if (!error)
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return nameidata_to_filp(&nd, flags);
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