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Coda: add spin lock to protect accesses to struct coda_inode_info.

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We mostly need it to protect cached user permissions. The c_flags field
is advisory, reading the wrong value is harmless and in the worst case
we hit a slow path where we have to make an extra upcall to the
userspace cache manager when revalidating a dentry or inode.

Signed-off-by: Yoshihisa Abe <yoshiabe@cs.cmu.edu>
Signed-off-by: Jan Harkes <jaharkes@cs.cmu.edu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Yoshihisa Abe
2010-10-25 02:03:44 -04:00
committed by Linus Torvalds
parent 3a99c63190
commit b5ce1d83a6
7 changed files with 58 additions and 17 deletions
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19
fs/coda/cnode.c
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@@ -45,13 +45,15 @@ static void coda_fill_inode(struct inode *inode, struct coda_vattr *attr)
static int coda_test_inode(struct inode *inode, void *data)
{
struct CodaFid *fid = (struct CodaFid *)data;
return coda_fideq(&(ITOC(inode)->c_fid), fid);
struct coda_inode_info *cii = ITOC(inode);
return coda_fideq(&cii->c_fid, fid);
}
static int coda_set_inode(struct inode *inode, void *data)
{
struct CodaFid *fid = (struct CodaFid *)data;
ITOC(inode)->c_fid = *fid;
struct coda_inode_info *cii = ITOC(inode);
cii->c_fid = *fid;
return 0;
}
@@ -71,6 +73,7 @@ struct inode * coda_iget(struct super_block * sb, struct CodaFid * fid,
cii = ITOC(inode);
/* we still need to set i_ino for things like stat(2) */
inode->i_ino = hash;
/* inode is locked and unique, no need to grab cii->c_lock */
cii->c_mapcount = 0;
unlock_new_inode(inode);
}
@@ -107,14 +110,20 @@ int coda_cnode_make(struct inode **inode, struct CodaFid *fid, struct super_bloc
}
/* Although we treat Coda file identifiers as immutable, there is one
* special case for files created during a disconnection where they may
* not be globally unique. When an identifier collision is detected we
* first try to flush the cached inode from the kernel and finally
* resort to renaming/rehashing in-place. Userspace remembers both old
* and new values of the identifier to handle any in-flight upcalls.
* The real solution is to use globally unique UUIDs as identifiers, but
* retrofitting the existing userspace code for this is non-trivial. */
void coda_replace_fid(struct inode *inode, struct CodaFid *oldfid,
struct CodaFid *newfid)
{
struct coda_inode_info *cii;
struct coda_inode_info *cii = ITOC(inode);
unsigned long hash = coda_f2i(newfid);
cii = ITOC(inode);
BUG_ON(!coda_fideq(&cii->c_fid, oldfid));
/* replace fid and rehash inode */