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author | Eric W. Biederman <ebiederm@xmission.com> | 2020-11-21 02:14:34 +0300 |
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committer | Eric W. Biederman <ebiederm@xmission.com> | 2020-12-10 21:42:58 +0300 |
commit | 775e0656b27210ae668e33af00bece858f44576f (patch) | |
tree | 246ddc8786c491d3c13b3f96d5d7fa73625aaed3 /fs/file.c | |
parent | 66ed594409a10b1cc6fa1e8d22bc8aed2a080d0c (diff) | |
download | linux-775e0656b27210ae668e33af00bece858f44576f.tar.xz |
proc/fd: In fdinfo seq_show don't use get_files_struct
When discussing[1] exec and posix file locks it was realized that none
of the callers of get_files_struct fundamentally needed to call
get_files_struct, and that by switching them to helper functions
instead it will both simplify their code and remove unnecessary
increments of files_struct.count. Those unnecessary increments can
result in exec unnecessarily unsharing files_struct which breaking
posix locks, and it can result in fget_light having to fallback to
fget reducing system performance.
Instead hold task_lock for the duration that task->files needs to be
stable in seq_show. The task_lock was already taken in
get_files_struct, and so skipping get_files_struct performs less work
overall, and avoids the problems with the files_struct reference
count.
[1] https://lkml.kernel.org/r/20180915160423.GA31461@redhat.com
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
v1: https://lkml.kernel.org/r/20200817220425.9389-12-ebiederm@xmission.com
Link: https://lkml.kernel.org/r/20201120231441.29911-17-ebiederm@xmission.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Diffstat (limited to 'fs/file.c')
0 files changed, 0 insertions, 0 deletions