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| author | David S. Miller <davem@davemloft.net> | 2010-03-15 23:23:54 (GMT) |
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| committer | David S. Miller <davem@davemloft.net> | 2010-03-15 23:23:54 (GMT) |
| commit | 4961e02f1999e1c3468c09b2669c94d7c3ae82a8 (patch) | |
| tree | 44c15abb09d7ba5e17a9aba95ee246648b1c1a8a /Documentation/filesystems/sharedsubtree.txt | |
| parent | d14a0ebda7d3daede1a99c01527affb9ceaa4c22 (diff) | |
| parent | a3d3203e4bb40f253b1541e310dc0f9305be7c84 (diff) | |
| download | linux-fsl-qoriq-4961e02f1999e1c3468c09b2669c94d7c3ae82a8.tar.xz | |
Merge branch 'master' of /home/davem/src/GIT/linux-2.6/
Diffstat (limited to 'Documentation/filesystems/sharedsubtree.txt')
| -rw-r--r-- | Documentation/filesystems/sharedsubtree.txt | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/Documentation/filesystems/sharedsubtree.txt b/Documentation/filesystems/sharedsubtree.txt index 23a1810..fc0e39a 100644 --- a/Documentation/filesystems/sharedsubtree.txt +++ b/Documentation/filesystems/sharedsubtree.txt @@ -837,6 +837,9 @@ replicas continue to be exactly same. individual lists does not affect propagation or the way propagation tree is modified by operations. + All vfsmounts in a peer group have the same ->mnt_master. If it is + non-NULL, they form a contiguous (ordered) segment of slave list. + A example propagation tree looks as shown in the figure below. [ NOTE: Though it looks like a forest, if we consider all the shared mounts as a conceptual entity called 'pnode', it becomes a tree] @@ -874,8 +877,19 @@ replicas continue to be exactly same. NOTE: The propagation tree is orthogonal to the mount tree. +8B Locking: + + ->mnt_share, ->mnt_slave, ->mnt_slave_list, ->mnt_master are protected + by namespace_sem (exclusive for modifications, shared for reading). + + Normally we have ->mnt_flags modifications serialized by vfsmount_lock. + There are two exceptions: do_add_mount() and clone_mnt(). + The former modifies a vfsmount that has not been visible in any shared + data structures yet. + The latter holds namespace_sem and the only references to vfsmount + are in lists that can't be traversed without namespace_sem. -8B Algorithm: +8C Algorithm: The crux of the implementation resides in rbind/move operation. |