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f03c65993b
Instead of splitting refcount between (per-cpu) mnt_count and (SMP-only) mnt_longrefs, make all references contribute to mnt_count again and keep track of how many are longterm ones. Accounting rules for longterm count: * 1 for each fs_struct.root.mnt * 1 for each fs_struct.pwd.mnt * 1 for having non-NULL ->mnt_ns * decrement to 0 happens only under vfsmount lock exclusive That allows nice common case for mntput() - since we can't drop the final reference until after mnt_longterm has reached 0 due to the rules above, mntput() can grab vfsmount lock shared and check mnt_longterm. If it turns out to be non-zero (which is the common case), we know that this is not the final mntput() and can just blindly decrement percpu mnt_count. Otherwise we grab vfsmount lock exclusive and do usual decrement-and-check of percpu mnt_count. For fs_struct.c we have mnt_make_longterm() and mnt_make_shortterm(); namespace.c uses the latter in places where we don't already hold vfsmount lock exclusive and opencodes a few remaining spots where we need to manipulate mnt_longterm. Note that we mostly revert the code outside of fs/namespace.c back to what we used to have; in particular, normal code doesn't need to care about two kinds of references, etc. And we get to keep the optimization Nick's variant had bought us... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> |
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| .. | ||
| chips | ||
| devices | ||
| lpddr | ||
| maps | ||
| nand | ||
| onenand | ||
| tests | ||
| ubi | ||
| afs.c | ||
| ar7part.c | ||
| cmdlinepart.c | ||
| ftl.c | ||
| inftlcore.c | ||
| inftlmount.c | ||
| Kconfig | ||
| Makefile | ||
| mtd_blkdevs.c | ||
| mtdblock_ro.c | ||
| mtdblock.c | ||
| mtdchar.c | ||
| mtdconcat.c | ||
| mtdcore.c | ||
| mtdcore.h | ||
| mtdoops.c | ||
| mtdpart.c | ||
| mtdsuper.c | ||
| nftlcore.c | ||
| nftlmount.c | ||
| ofpart.c | ||
| redboot.c | ||
| rfd_ftl.c | ||
| sm_ftl.c | ||
| sm_ftl.h | ||
| ssfdc.c | ||