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Dan Magenheimer
38b5faf4b1
This patch, 2of4, contains the changes to the core swap subsystem. This includes: (1) makes available core swap data structures (swap_lock, swap_list and swap_info) that are needed by frontswap.c but we don't need to expose them to the dozens of files that include swap.h so we create a new swapfile.h just to extern-ify these and modify their declarations to non-static (2) adds frontswap-related elements to swap_info_struct. Frontswap_map points to vzalloc'ed one-bit-per-swap-page metadata that indicates whether the swap page is in frontswap or in the device and frontswap_pages counts how many pages are in frontswap. (3) adds hooks in the swap subsystem and extends try_to_unuse so that frontswap_shrink can do a "partial swapoff". Note that a failed frontswap_map allocation is safe... failure is noted by lack of "FS" in the subsequent printk. --- [v14: rebase to 3.4-rc2] [v10: no change] [v9: [email protected]: mark some statics __read_mostly] [v9: [email protected]: add clarifying comments] [v9: [email protected]: no need to loop repeating try_to_unuse] [v9: [email protected]: remove superfluous check for NULL] [v8: rebase to 3.0-rc4] [v8: [email protected]: change counter to atomic_t to avoid races] [v8: [email protected]: comment to clarify informational counters] [v7: rebase to 3.0-rc3] [v7: [email protected]: add new swap struct elements only if config'd] [v6: rebase to 3.0-rc1] [v6: [email protected]: fix null pointer deref if vzalloc fails] [v6: [email protected]: various checks and code clarifications/comments] [v5: no change from v4] [v4: rebase to 2.6.39] Signed-off-by: Dan Magenheimer <[email protected]> Reviewed-by: Kamezawa Hiroyuki <[email protected]> Acked-by: Jan Beulich <[email protected]> Acked-by: Seth Jennings <[email protected]> Cc: Jeremy Fitzhardinge <[email protected]> Cc: Hugh Dickins <[email protected]> Cc: Johannes Weiner <[email protected]> Cc: Nitin Gupta <[email protected]> Cc: Matthew Wilcox <[email protected]> Cc: Chris Mason <[email protected]> Cc: Rik Riel <[email protected]> Cc: Andrew Morton <[email protected]> [v11: Rebased, fixed mm/swapfile.c context change] Signed-off-by: Konrad Rzeszutek Wilk <[email protected]>
14 lines
411 B
C
14 lines
411 B
C
#ifndef _LINUX_SWAPFILE_H
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#define _LINUX_SWAPFILE_H
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/*
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* these were static in swapfile.c but frontswap.c needs them and we don't
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* want to expose them to the dozens of source files that include swap.h
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*/
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extern spinlock_t swap_lock;
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extern struct swap_list_t swap_list;
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extern struct swap_info_struct *swap_info[];
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extern int try_to_unuse(unsigned int, bool, unsigned long);
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#endif /* _LINUX_SWAPFILE_H */
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