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author | Michal Hocko <mhocko@suse.com> | 2018-05-29 10:26:44 +0200 |
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committer | Jonathan Corbet <corbet@lwn.net> | 2018-05-29 06:45:42 -0600 |
commit | 46ca359955fee63486dc1cfc528ae5692bb16dcd (patch) | |
tree | 5b50eea6676820b268168e0dd9ab4c7b9a2c5b1a /include/linux/sched | |
parent | 8962e40c19933a11bb5c46216e36ca4d63751c3e (diff) | |
download | linux-stable-46ca359955fee63486dc1cfc528ae5692bb16dcd.tar.gz linux-stable-46ca359955fee63486dc1cfc528ae5692bb16dcd.tar.bz2 linux-stable-46ca359955fee63486dc1cfc528ae5692bb16dcd.zip |
doc: document scope NOFS, NOIO APIs
Although the api is documented in the source code Ted has pointed out
that there is no mention in the core-api Documentation and there are
people looking there to find answers how to use a specific API.
Requested-by: "Theodore Y. Ts'o" <tytso@mit.edu>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Diffstat (limited to 'include/linux/sched')
-rw-r--r-- | include/linux/sched/mm.h | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h index 4e1411bbbcfc..76a8cb4ef178 100644 --- a/include/linux/sched/mm.h +++ b/include/linux/sched/mm.h @@ -170,6 +170,17 @@ static inline void fs_reclaim_acquire(gfp_t gfp_mask) { } static inline void fs_reclaim_release(gfp_t gfp_mask) { } #endif +/** + * memalloc_noio_save - Marks implicit GFP_NOIO allocation scope. + * + * This functions marks the beginning of the GFP_NOIO allocation scope. + * All further allocations will implicitly drop __GFP_IO flag and so + * they are safe for the IO critical section from the allocation recursion + * point of view. Use memalloc_noio_restore to end the scope with flags + * returned by this function. + * + * This function is safe to be used from any context. + */ static inline unsigned int memalloc_noio_save(void) { unsigned int flags = current->flags & PF_MEMALLOC_NOIO; @@ -177,11 +188,30 @@ static inline unsigned int memalloc_noio_save(void) return flags; } +/** + * memalloc_noio_restore - Ends the implicit GFP_NOIO scope. + * @flags: Flags to restore. + * + * Ends the implicit GFP_NOIO scope started by memalloc_noio_save function. + * Always make sure that that the given flags is the return value from the + * pairing memalloc_noio_save call. + */ static inline void memalloc_noio_restore(unsigned int flags) { current->flags = (current->flags & ~PF_MEMALLOC_NOIO) | flags; } +/** + * memalloc_nofs_save - Marks implicit GFP_NOFS allocation scope. + * + * This functions marks the beginning of the GFP_NOFS allocation scope. + * All further allocations will implicitly drop __GFP_FS flag and so + * they are safe for the FS critical section from the allocation recursion + * point of view. Use memalloc_nofs_restore to end the scope with flags + * returned by this function. + * + * This function is safe to be used from any context. + */ static inline unsigned int memalloc_nofs_save(void) { unsigned int flags = current->flags & PF_MEMALLOC_NOFS; @@ -189,6 +219,14 @@ static inline unsigned int memalloc_nofs_save(void) return flags; } +/** + * memalloc_nofs_restore - Ends the implicit GFP_NOFS scope. + * @flags: Flags to restore. + * + * Ends the implicit GFP_NOFS scope started by memalloc_nofs_save function. + * Always make sure that that the given flags is the return value from the + * pairing memalloc_nofs_save call. + */ static inline void memalloc_nofs_restore(unsigned int flags) { current->flags = (current->flags & ~PF_MEMALLOC_NOFS) | flags; |