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| author | Yoshihisa Abe <yoshiabe@cs.cmu.edu> | 2010-10-25 10:03:44 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-10-25 19:02:40 +0400 |
| commit | b5ce1d83a62fc109d8e815b1fc71dcdb0d26bc49 (patch) | |
| tree | ea537c1b6436c36bee3b33d8b4f750124fd7d661 /fs/coda/file.c | |
| parent | 3a99c6319064af3f2e18eb929f638d555dbf7a62 (diff) | |
| download | linux-b5ce1d83a62fc109d8e815b1fc71dcdb0d26bc49.tar.xz | |
Coda: add spin lock to protect accesses to struct coda_inode_info.
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>
Diffstat (limited to 'fs/coda/file.c')
| -rw-r--r-- | fs/coda/file.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/fs/coda/file.c b/fs/coda/file.c index ad3cd2abeeb4..c4e395781d41 100644 --- a/fs/coda/file.c +++ b/fs/coda/file.c @@ -16,6 +16,7 @@ #include <linux/cred.h> #include <linux/errno.h> #include <linux/smp_lock.h> +#include <linux/spinlock.h> #include <linux/string.h> #include <linux/slab.h> #include <asm/uaccess.h> @@ -109,19 +110,24 @@ coda_file_mmap(struct file *coda_file, struct vm_area_struct *vma) coda_inode = coda_file->f_path.dentry->d_inode; host_inode = host_file->f_path.dentry->d_inode; + + cii = ITOC(coda_inode); + spin_lock(&cii->c_lock); coda_file->f_mapping = host_file->f_mapping; if (coda_inode->i_mapping == &coda_inode->i_data) coda_inode->i_mapping = host_inode->i_mapping; /* only allow additional mmaps as long as userspace isn't changing * the container file on us! */ - else if (coda_inode->i_mapping != host_inode->i_mapping) + else if (coda_inode->i_mapping != host_inode->i_mapping) { + spin_unlock(&cii->c_lock); return -EBUSY; + } /* keep track of how often the coda_inode/host_file has been mmapped */ - cii = ITOC(coda_inode); cii->c_mapcount++; cfi->cfi_mapcount++; + spin_unlock(&cii->c_lock); return host_file->f_op->mmap(host_file, vma); } @@ -185,11 +191,13 @@ int coda_release(struct inode *coda_inode, struct file *coda_file) cii = ITOC(coda_inode); /* did we mmap this file? */ + spin_lock(&cii->c_lock); if (coda_inode->i_mapping == &host_inode->i_data) { cii->c_mapcount -= cfi->cfi_mapcount; if (!cii->c_mapcount) coda_inode->i_mapping = &coda_inode->i_data; } + spin_unlock(&cii->c_lock); fput(cfi->cfi_container); kfree(coda_file->private_data); |