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b9cd542763
[ Upstream commit ef07b74e1be56f9eafda6aadebb9ebba0743c9f0 ]
There's a race between checking if an inode was logged before and logging
an inode that can cause us to mark an inode as not logged just after it
was logged by a concurrent task:
1) We have inode X which was not logged before neither in the current
transaction not in past transaction since the inode was loaded into
memory, so it's ->logged_trans value is 0;
2) We are at transaction N;
3) Task A calls inode_logged() against inode X, sees that ->logged_trans
is 0 and there is a log tree and so it proceeds to search in the log
tree for an inode item for inode X. It doesn't see any, but before
it sets ->logged_trans to N - 1...
3) Task B calls btrfs_log_inode() against inode X, logs the inode and
sets ->logged_trans to N;
4) Task A now sets ->logged_trans to N - 1;
5) At this point anyone calling inode_logged() gets 0 (inode not logged)
since ->logged_trans is greater than 0 and less than N, but our inode
was really logged. As a consequence operations like rename, unlink and
link that happen afterwards in the current transaction end up not
updating the log when they should.
Fix this by ensuring inode_logged() only updates ->logged_trans in case
the inode item is not found in the log tree if after tacking the inode's
lock (spinlock struct btrfs_inode::lock) the ->logged_trans value is still
zero, since the inode lock is what protects setting ->logged_trans at
btrfs_log_inode().
Fixes:
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||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
There are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. Please read Documentation/admin-guide/README.rst first.
In order to build the documentation, use make htmldocs or
make pdfdocs. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.