linux/net/sunrpc/cache.c

1856 lines
44 KiB

sunrpc/cache: make cache flushing more reliable. The caches used to store sunrpc authentication information can be flushed by writing a timestamp to a file in /proc. This timestamp has a one-second resolution and any entry in cache that was last_refreshed *before* that time is treated as expired. This is problematic as it is not possible to reliably flush the cache without interrupting NFS service. If the current time is written to the "flush" file, any entry that was added since the current second started will still be treated as valid. If one second beyond than the current time is written to the file then no entries can be valid until the second ticks over. This will mean that no NFS request will be handled for up to 1 second. To resolve this issue we make two changes: 1/ treat an entry as expired if the timestamp when it was last_refreshed is before *or the same as* the expiry time. This means that current code which writes out the current time will now flush the cache reliably. 2/ when a new entry in added to the cache - set the last_refresh timestamp to 1 second *beyond* the current flush time, when that not in the past. This ensures that newly added entries will always be valid. Now that we have a very reliable way to flush the cache, and also since we are using "since-boot" timestamps which are monotonic, change cache_purge() to set the smallest future flush_time which will work, and leave it there: don't revert to '1'. Also disable the setting of the 'flush_time' far into the future. That has never been useful and is now awkward as it would cause last_refresh times to be strange. Finally: if a request is made to set the 'flush_time' to the current second, assume the intent is to flush the cache and advance it, if necessary, to 1 second beyond the current 'flush_time' so that all active entries will be deemed to be expired. As part of this we need to add a 'cache_detail' arg to cache_init() and cache_fresh_locked() so they can find the current ->flush_time. Signed-off-by: NeilBrown <neilb@suse.com> Reported-by: Olaf Kirch <okir@suse.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2015-10-16 08:59:08 +11:00
sunrpc/cache: make cache flushing more reliable. The caches used to store sunrpc authentication information can be flushed by writing a timestamp to a file in /proc. This timestamp has a one-second resolution and any entry in cache that was last_refreshed *before* that time is treated as expired. This is problematic as it is not possible to reliably flush the cache without interrupting NFS service. If the current time is written to the "flush" file, any entry that was added since the current second started will still be treated as valid. If one second beyond than the current time is written to the file then no entries can be valid until the second ticks over. This will mean that no NFS request will be handled for up to 1 second. To resolve this issue we make two changes: 1/ treat an entry as expired if the timestamp when it was last_refreshed is before *or the same as* the expiry time. This means that current code which writes out the current time will now flush the cache reliably. 2/ when a new entry in added to the cache - set the last_refresh timestamp to 1 second *beyond* the current flush time, when that not in the past. This ensures that newly added entries will always be valid. Now that we have a very reliable way to flush the cache, and also since we are using "since-boot" timestamps which are monotonic, change cache_purge() to set the smallest future flush_time which will work, and leave it there: don't revert to '1'. Also disable the setting of the 'flush_time' far into the future. That has never been useful and is now awkward as it would cause last_refresh times to be strange. Finally: if a request is made to set the 'flush_time' to the current second, assume the intent is to flush the cache and advance it, if necessary, to 1 second beyond the current 'flush_time' so that all active entries will be deemed to be expired. As part of this we need to add a 'cache_detail' arg to cache_init() and cache_fresh_locked() so they can find the current ->flush_time. Signed-off-by: NeilBrown <neilb@suse.com> Reported-by: Olaf Kirch <okir@suse.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2015-10-16 08:59:08 +11:00
sunrpc/cache: make cache flushing more reliable. The caches used to store sunrpc authentication information can be flushed by writing a timestamp to a file in /proc. This timestamp has a one-second resolution and any entry in cache that was last_refreshed *before* that time is treated as expired. This is problematic as it is not possible to reliably flush the cache without interrupting NFS service. If the current time is written to the "flush" file, any entry that was added since the current second started will still be treated as valid. If one second beyond than the current time is written to the file then no entries can be valid until the second ticks over. This will mean that no NFS request will be handled for up to 1 second. To resolve this issue we make two changes: 1/ treat an entry as expired if the timestamp when it was last_refreshed is before *or the same as* the expiry time. This means that current code which writes out the current time will now flush the cache reliably. 2/ when a new entry in added to the cache - set the last_refresh timestamp to 1 second *beyond* the current flush time, when that not in the past. This ensures that newly added entries will always be valid. Now that we have a very reliable way to flush the cache, and also since we are using "since-boot" timestamps which are monotonic, change cache_purge() to set the smallest future flush_time which will work, and leave it there: don't revert to '1'. Also disable the setting of the 'flush_time' far into the future. That has never been useful and is now awkward as it would cause last_refresh times to be strange. Finally: if a request is made to set the 'flush_time' to the current second, assume the intent is to flush the cache and advance it, if necessary, to 1 second beyond the current 'flush_time' so that all active entries will be deemed to be expired. As part of this we need to add a 'cache_detail' arg to cache_init() and cache_fresh_locked() so they can find the current ->flush_time. Signed-off-by: NeilBrown <neilb@suse.com> Reported-by: Olaf Kirch <okir@suse.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2015-10-16 08:59:08 +11:00
sunrpc/cache: make cache flushing more reliable. The caches used to store sunrpc authentication information can be flushed by writing a timestamp to a file in /proc. This timestamp has a one-second resolution and any entry in cache that was last_refreshed *before* that time is treated as expired. This is problematic as it is not possible to reliably flush the cache without interrupting NFS service. If the current time is written to the "flush" file, any entry that was added since the current second started will still be treated as valid. If one second beyond than the current time is written to the file then no entries can be valid until the second ticks over. This will mean that no NFS request will be handled for up to 1 second. To resolve this issue we make two changes: 1/ treat an entry as expired if the timestamp when it was last_refreshed is before *or the same as* the expiry time. This means that current code which writes out the current time will now flush the cache reliably. 2/ when a new entry in added to the cache - set the last_refresh timestamp to 1 second *beyond* the current flush time, when that not in the past. This ensures that newly added entries will always be valid. Now that we have a very reliable way to flush the cache, and also since we are using "since-boot" timestamps which are monotonic, change cache_purge() to set the smallest future flush_time which will work, and leave it there: don't revert to '1'. Also disable the setting of the 'flush_time' far into the future. That has never been useful and is now awkward as it would cause last_refresh times to be strange. Finally: if a request is made to set the 'flush_time' to the current second, assume the intent is to flush the cache and advance it, if necessary, to 1 second beyond the current 'flush_time' so that all active entries will be deemed to be expired. As part of this we need to add a 'cache_detail' arg to cache_init() and cache_fresh_locked() so they can find the current ->flush_time. Signed-off-by: NeilBrown <neilb@suse.com> Reported-by: Olaf Kirch <okir@suse.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2015-10-16 08:59:08 +11:00
sunrpc/cache: make cache flushing more reliable. The caches used to store sunrpc authentication information can be flushed by writing a timestamp to a file in /proc. This timestamp has a one-second resolution and any entry in cache that was last_refreshed *before* that time is treated as expired. This is problematic as it is not possible to reliably flush the cache without interrupting NFS service. If the current time is written to the "flush" file, any entry that was added since the current second started will still be treated as valid. If one second beyond than the current time is written to the file then no entries can be valid until the second ticks over. This will mean that no NFS request will be handled for up to 1 second. To resolve this issue we make two changes: 1/ treat an entry as expired if the timestamp when it was last_refreshed is before *or the same as* the expiry time. This means that current code which writes out the current time will now flush the cache reliably. 2/ when a new entry in added to the cache - set the last_refresh timestamp to 1 second *beyond* the current flush time, when that not in the past. This ensures that newly added entries will always be valid. Now that we have a very reliable way to flush the cache, and also since we are using "since-boot" timestamps which are monotonic, change cache_purge() to set the smallest future flush_time which will work, and leave it there: don't revert to '1'. Also disable the setting of the 'flush_time' far into the future. That has never been useful and is now awkward as it would cause last_refresh times to be strange. Finally: if a request is made to set the 'flush_time' to the current second, assume the intent is to flush the cache and advance it, if necessary, to 1 second beyond the current 'flush_time' so that all active entries will be deemed to be expired. As part of this we need to add a 'cache_detail' arg to cache_init() and cache_fresh_locked() so they can find the current ->flush_time. Signed-off-by: NeilBrown <neilb@suse.com> Reported-by: Olaf Kirch <okir@suse.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2015-10-16 08:59:08 +11:00
sunrpc/cache: make cache flushing more reliable. The caches used to store sunrpc authentication information can be flushed by writing a timestamp to a file in /proc. This timestamp has a one-second resolution and any entry in cache that was last_refreshed *before* that time is treated as expired. This is problematic as it is not possible to reliably flush the cache without interrupting NFS service. If the current time is written to the "flush" file, any entry that was added since the current second started will still be treated as valid. If one second beyond than the current time is written to the file then no entries can be valid until the second ticks over. This will mean that no NFS request will be handled for up to 1 second. To resolve this issue we make two changes: 1/ treat an entry as expired if the timestamp when it was last_refreshed is before *or the same as* the expiry time. This means that current code which writes out the current time will now flush the cache reliably. 2/ when a new entry in added to the cache - set the last_refresh timestamp to 1 second *beyond* the current flush time, when that not in the past. This ensures that newly added entries will always be valid. Now that we have a very reliable way to flush the cache, and also since we are using "since-boot" timestamps which are monotonic, change cache_purge() to set the smallest future flush_time which will work, and leave it there: don't revert to '1'. Also disable the setting of the 'flush_time' far into the future. That has never been useful and is now awkward as it would cause last_refresh times to be strange. Finally: if a request is made to set the 'flush_time' to the current second, assume the intent is to flush the cache and advance it, if necessary, to 1 second beyond the current 'flush_time' so that all active entries will be deemed to be expired. As part of this we need to add a 'cache_detail' arg to cache_init() and cache_fresh_locked() so they can find the current ->flush_time. Signed-off-by: NeilBrown <neilb@suse.com> Reported-by: Olaf Kirch <okir@suse.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2015-10-16 08:59:08 +11:00
sunrpc/cache: make cache flushing more reliable. The caches used to store sunrpc authentication information can be flushed by writing a timestamp to a file in /proc. This timestamp has a one-second resolution and any entry in cache that was last_refreshed *before* that time is treated as expired. This is problematic as it is not possible to reliably flush the cache without interrupting NFS service. If the current time is written to the "flush" file, any entry that was added since the current second started will still be treated as valid. If one second beyond than the current time is written to the file then no entries can be valid until the second ticks over. This will mean that no NFS request will be handled for up to 1 second. To resolve this issue we make two changes: 1/ treat an entry as expired if the timestamp when it was last_refreshed is before *or the same as* the expiry time. This means that current code which writes out the current time will now flush the cache reliably. 2/ when a new entry in added to the cache - set the last_refresh timestamp to 1 second *beyond* the current flush time, when that not in the past. This ensures that newly added entries will always be valid. Now that we have a very reliable way to flush the cache, and also since we are using "since-boot" timestamps which are monotonic, change cache_purge() to set the smallest future flush_time which will work, and leave it there: don't revert to '1'. Also disable the setting of the 'flush_time' far into the future. That has never been useful and is now awkward as it would cause last_refresh times to be strange. Finally: if a request is made to set the 'flush_time' to the current second, assume the intent is to flush the cache and advance it, if necessary, to 1 second beyond the current 'flush_time' so that all active entries will be deemed to be expired. As part of this we need to add a 'cache_detail' arg to cache_init() and cache_fresh_locked() so they can find the current ->flush_time. Signed-off-by: NeilBrown <neilb@suse.com> Reported-by: Olaf Kirch <okir@suse.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2015-10-16 08:59:08 +11:00
sunrpc/cache: make cache flushing more reliable. The caches used to store sunrpc authentication information can be flushed by writing a timestamp to a file in /proc. This timestamp has a one-second resolution and any entry in cache that was last_refreshed *before* that time is treated as expired. This is problematic as it is not possible to reliably flush the cache without interrupting NFS service. If the current time is written to the "flush" file, any entry that was added since the current second started will still be treated as valid. If one second beyond than the current time is written to the file then no entries can be valid until the second ticks over. This will mean that no NFS request will be handled for up to 1 second. To resolve this issue we make two changes: 1/ treat an entry as expired if the timestamp when it was last_refreshed is before *or the same as* the expiry time. This means that current code which writes out the current time will now flush the cache reliably. 2/ when a new entry in added to the cache - set the last_refresh timestamp to 1 second *beyond* the current flush time, when that not in the past. This ensures that newly added entries will always be valid. Now that we have a very reliable way to flush the cache, and also since we are using "since-boot" timestamps which are monotonic, change cache_purge() to set the smallest future flush_time which will work, and leave it there: don't revert to '1'. Also disable the setting of the 'flush_time' far into the future. That has never been useful and is now awkward as it would cause last_refresh times to be strange. Finally: if a request is made to set the 'flush_time' to the current second, assume the intent is to flush the cache and advance it, if necessary, to 1 second beyond the current 'flush_time' so that all active entries will be deemed to be expired. As part of this we need to add a 'cache_detail' arg to cache_init() and cache_fresh_locked() so they can find the current ->flush_time. Signed-off-by: NeilBrown <neilb@suse.com> Reported-by: Olaf Kirch <okir@suse.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2015-10-16 08:59:08 +11:00
sunrpc/cache: make cache flushing more reliable. The caches used to store sunrpc authentication information can be flushed by writing a timestamp to a file in /proc. This timestamp has a one-second resolution and any entry in cache that was last_refreshed *before* that time is treated as expired. This is problematic as it is not possible to reliably flush the cache without interrupting NFS service. If the current time is written to the "flush" file, any entry that was added since the current second started will still be treated as valid. If one second beyond than the current time is written to the file then no entries can be valid until the second ticks over. This will mean that no NFS request will be handled for up to 1 second. To resolve this issue we make two changes: 1/ treat an entry as expired if the timestamp when it was last_refreshed is before *or the same as* the expiry time. This means that current code which writes out the current time will now flush the cache reliably. 2/ when a new entry in added to the cache - set the last_refresh timestamp to 1 second *beyond* the current flush time, when that not in the past. This ensures that newly added entries will always be valid. Now that we have a very reliable way to flush the cache, and also since we are using "since-boot" timestamps which are monotonic, change cache_purge() to set the smallest future flush_time which will work, and leave it there: don't revert to '1'. Also disable the setting of the 'flush_time' far into the future. That has never been useful and is now awkward as it would cause last_refresh times to be strange. Finally: if a request is made to set the 'flush_time' to the current second, assume the intent is to flush the cache and advance it, if necessary, to 1 second beyond the current 'flush_time' so that all active entries will be deemed to be expired. As part of this we need to add a 'cache_detail' arg to cache_init() and cache_fresh_locked() so they can find the current ->flush_time. Signed-off-by: NeilBrown <neilb@suse.com> Reported-by: Olaf Kirch <okir@suse.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2015-10-16 08:59:08 +11:00
sunrpc/cache: use cache_fresh_unlocked consistently and correctly. cache_fresh_unlocked() is called when a cache entry has been updated and ensures that if there were any pending upcalls, they are cleared. So every time we update a cache entry, we should call this, and this should be the only way that we try to clear pending calls (that sort of uniformity makes code sooo much easier to read). try_to_negate_entry() will (possibly) mark an entry as negative. If it doesn't, it is because the entry already is VALID. So the entry will be valid on exit, so it is appropriate to call cache_fresh_unlocked(). So tidy up try_to_negate_entry() to do that, and remove partial open-coded cache_fresh_unlocked() from the one call-site of try_to_negate_entry(). In the other branch of the 'switch(cache_make_upcall())', we again have a partial open-coded version of cache_fresh_unlocked(). Replace that with a real call. And again in cache_clean(), use a real call to cache_fresh_unlocked(). These call sites might previously have called cache_revisit_request() if CACHE_PENDING wasn't set. This is never necessary because cache_revisit_request() can only do anything if the item is in the cache_defer_hash, However any time that an item is added to the cache_defer_hash (setup_deferral), the code immediately tests CACHE_PENDING, and removes the entry again if it is clear. So all other places we only need to 'cache_revisit_request' if we've just cleared CACHE_PENDING. Reported-by: Bodo Stroesser <bstroesser@ts.fujitsu.com> Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2013-06-13 12:53:42 +10:00
sunrpc/cache: make cache flushing more reliable. The caches used to store sunrpc authentication information can be flushed by writing a timestamp to a file in /proc. This timestamp has a one-second resolution and any entry in cache that was last_refreshed *before* that time is treated as expired. This is problematic as it is not possible to reliably flush the cache without interrupting NFS service. If the current time is written to the "flush" file, any entry that was added since the current second started will still be treated as valid. If one second beyond than the current time is written to the file then no entries can be valid until the second ticks over. This will mean that no NFS request will be handled for up to 1 second. To resolve this issue we make two changes: 1/ treat an entry as expired if the timestamp when it was last_refreshed is before *or the same as* the expiry time. This means that current code which writes out the current time will now flush the cache reliably. 2/ when a new entry in added to the cache - set the last_refresh timestamp to 1 second *beyond* the current flush time, when that not in the past. This ensures that newly added entries will always be valid. Now that we have a very reliable way to flush the cache, and also since we are using "since-boot" timestamps which are monotonic, change cache_purge() to set the smallest future flush_time which will work, and leave it there: don't revert to '1'. Also disable the setting of the 'flush_time' far into the future. That has never been useful and is now awkward as it would cause last_refresh times to be strange. Finally: if a request is made to set the 'flush_time' to the current second, assume the intent is to flush the cache and advance it, if necessary, to 1 second beyond the current 'flush_time' so that all active entries will be deemed to be expired. As part of this we need to add a 'cache_detail' arg to cache_init() and cache_fresh_locked() so they can find the current ->flush_time. Signed-off-by: NeilBrown <neilb@suse.com> Reported-by: Olaf Kirch <okir@suse.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2015-10-16 08:59:08 +11:00
sunrpc/cache: use cache_fresh_unlocked consistently and correctly. cache_fresh_unlocked() is called when a cache entry has been updated and ensures that if there were any pending upcalls, they are cleared. So every time we update a cache entry, we should call this, and this should be the only way that we try to clear pending calls (that sort of uniformity makes code sooo much easier to read). try_to_negate_entry() will (possibly) mark an entry as negative. If it doesn't, it is because the entry already is VALID. So the entry will be valid on exit, so it is appropriate to call cache_fresh_unlocked(). So tidy up try_to_negate_entry() to do that, and remove partial open-coded cache_fresh_unlocked() from the one call-site of try_to_negate_entry(). In the other branch of the 'switch(cache_make_upcall())', we again have a partial open-coded version of cache_fresh_unlocked(). Replace that with a real call. And again in cache_clean(), use a real call to cache_fresh_unlocked(). These call sites might previously have called cache_revisit_request() if CACHE_PENDING wasn't set. This is never necessary because cache_revisit_request() can only do anything if the item is in the cache_defer_hash, However any time that an item is added to the cache_defer_hash (setup_deferral), the code immediately tests CACHE_PENDING, and removes the entry again if it is clear. So all other places we only need to 'cache_revisit_request' if we've just cleared CACHE_PENDING. Reported-by: Bodo Stroesser <bstroesser@ts.fujitsu.com> Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2013-06-13 12:53:42 +10:00
sunrpc/cache: use cache_fresh_unlocked consistently and correctly. cache_fresh_unlocked() is called when a cache entry has been updated and ensures that if there were any pending upcalls, they are cleared. So every time we update a cache entry, we should call this, and this should be the only way that we try to clear pending calls (that sort of uniformity makes code sooo much easier to read). try_to_negate_entry() will (possibly) mark an entry as negative. If it doesn't, it is because the entry already is VALID. So the entry will be valid on exit, so it is appropriate to call cache_fresh_unlocked(). So tidy up try_to_negate_entry() to do that, and remove partial open-coded cache_fresh_unlocked() from the one call-site of try_to_negate_entry(). In the other branch of the 'switch(cache_make_upcall())', we again have a partial open-coded version of cache_fresh_unlocked(). Replace that with a real call. And again in cache_clean(), use a real call to cache_fresh_unlocked(). These call sites might previously have called cache_revisit_request() if CACHE_PENDING wasn't set. This is never necessary because cache_revisit_request() can only do anything if the item is in the cache_defer_hash, However any time that an item is added to the cache_defer_hash (setup_deferral), the code immediately tests CACHE_PENDING, and removes the entry again if it is clear. So all other places we only need to 'cache_revisit_request' if we've just cleared CACHE_PENDING. Reported-by: Bodo Stroesser <bstroesser@ts.fujitsu.com> Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2013-06-13 12:53:42 +10:00
sunrpc/cache: use cache_fresh_unlocked consistently and correctly. cache_fresh_unlocked() is called when a cache entry has been updated and ensures that if there were any pending upcalls, they are cleared. So every time we update a cache entry, we should call this, and this should be the only way that we try to clear pending calls (that sort of uniformity makes code sooo much easier to read). try_to_negate_entry() will (possibly) mark an entry as negative. If it doesn't, it is because the entry already is VALID. So the entry will be valid on exit, so it is appropriate to call cache_fresh_unlocked(). So tidy up try_to_negate_entry() to do that, and remove partial open-coded cache_fresh_unlocked() from the one call-site of try_to_negate_entry(). In the other branch of the 'switch(cache_make_upcall())', we again have a partial open-coded version of cache_fresh_unlocked(). Replace that with a real call. And again in cache_clean(), use a real call to cache_fresh_unlocked(). These call sites might previously have called cache_revisit_request() if CACHE_PENDING wasn't set. This is never necessary because cache_revisit_request() can only do anything if the item is in the cache_defer_hash, However any time that an item is added to the cache_defer_hash (setup_deferral), the code immediately tests CACHE_PENDING, and removes the entry again if it is clear. So all other places we only need to 'cache_revisit_request' if we've just cleared CACHE_PENDING. Reported-by: Bodo Stroesser <bstroesser@ts.fujitsu.com> Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2013-06-13 12:53:42 +10:00
2006-11-22 14:55:48 +00:00
sunrpc/cache: use cache_fresh_unlocked consistently and correctly. cache_fresh_unlocked() is called when a cache entry has been updated and ensures that if there were any pending upcalls, they are cleared. So every time we update a cache entry, we should call this, and this should be the only way that we try to clear pending calls (that sort of uniformity makes code sooo much easier to read). try_to_negate_entry() will (possibly) mark an entry as negative. If it doesn't, it is because the entry already is VALID. So the entry will be valid on exit, so it is appropriate to call cache_fresh_unlocked(). So tidy up try_to_negate_entry() to do that, and remove partial open-coded cache_fresh_unlocked() from the one call-site of try_to_negate_entry(). In the other branch of the 'switch(cache_make_upcall())', we again have a partial open-coded version of cache_fresh_unlocked(). Replace that with a real call. And again in cache_clean(), use a real call to cache_fresh_unlocked(). These call sites might previously have called cache_revisit_request() if CACHE_PENDING wasn't set. This is never necessary because cache_revisit_request() can only do anything if the item is in the cache_defer_hash, However any time that an item is added to the cache_defer_hash (setup_deferral), the code immediately tests CACHE_PENDING, and removes the entry again if it is clear. So all other places we only need to 'cache_revisit_request' if we've just cleared CACHE_PENDING. Reported-by: Bodo Stroesser <bstroesser@ts.fujitsu.com> Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2013-06-13 12:53:42 +10:00
2006-11-22 14:55:48 +00:00
hlist: drop the node parameter from iterators I'm not sure why, but the hlist for each entry iterators were conceived list_for_each_entry(pos, head, member) The hlist ones were greedy and wanted an extra parameter: hlist_for_each_entry(tpos, pos, head, member) Why did they need an extra pos parameter? I'm not quite sure. Not only they don't really need it, it also prevents the iterator from looking exactly like the list iterator, which is unfortunate. Besides the semantic patch, there was some manual work required: - Fix up the actual hlist iterators in linux/list.h - Fix up the declaration of other iterators based on the hlist ones. - A very small amount of places were using the 'node' parameter, this was modified to use 'obj->member' instead. - Coccinelle didn't handle the hlist_for_each_entry_safe iterator properly, so those had to be fixed up manually. The semantic patch which is mostly the work of Peter Senna Tschudin is here: @@ iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host; type T; expression a,c,d,e; identifier b; statement S; @@ -T b; <+... when != b ( hlist_for_each_entry(a, - b, c, d) S | hlist_for_each_entry_continue(a, - b, c) S | hlist_for_each_entry_from(a, - b, c) S | hlist_for_each_entry_rcu(a, - b, c, d) S | hlist_for_each_entry_rcu_bh(a, - b, c, d) S | hlist_for_each_entry_continue_rcu_bh(a, - b, c) S | for_each_busy_worker(a, c, - b, d) S | ax25_uid_for_each(a, - b, c) S | ax25_for_each(a, - b, c) S | inet_bind_bucket_for_each(a, - b, c) S | sctp_for_each_hentry(a, - b, c) S | sk_for_each(a, - b, c) S | sk_for_each_rcu(a, - b, c) S | sk_for_each_from -(a, b) +(a) S + sk_for_each_from(a) S | sk_for_each_safe(a, - b, c, d) S | sk_for_each_bound(a, - b, c) S | hlist_for_each_entry_safe(a, - b, c, d, e) S | hlist_for_each_entry_continue_rcu(a, - b, c) S | nr_neigh_for_each(a, - b, c) S | nr_neigh_for_each_safe(a, - b, c, d) S | nr_node_for_each(a, - b, c) S | nr_node_for_each_safe(a, - b, c, d) S | - for_each_gfn_sp(a, c, d, b) S + for_each_gfn_sp(a, c, d) S | - for_each_gfn_indirect_valid_sp(a, c, d, b) S + for_each_gfn_indirect_valid_sp(a, c, d) S | for_each_host(a, - b, c) S | for_each_host_safe(a, - b, c, d) S | for_each_mesh_entry(a, - b, c, d) S ) ...+> [akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c] [akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c] [akpm@linux-foundation.org: checkpatch fixes] [akpm@linux-foundation.org: fix warnings] [akpm@linux-foudnation.org: redo intrusive kvm changes] Tested-by: Peter Senna Tschudin <peter.senna@gmail.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Gleb Natapov <gleb@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-27 17:06:00 -08:00
hlist: drop the node parameter from iterators I'm not sure why, but the hlist for each entry iterators were conceived list_for_each_entry(pos, head, member) The hlist ones were greedy and wanted an extra parameter: hlist_for_each_entry(tpos, pos, head, member) Why did they need an extra pos parameter? I'm not quite sure. Not only they don't really need it, it also prevents the iterator from looking exactly like the list iterator, which is unfortunate. Besides the semantic patch, there was some manual work required: - Fix up the actual hlist iterators in linux/list.h - Fix up the declaration of other iterators based on the hlist ones. - A very small amount of places were using the 'node' parameter, this was modified to use 'obj->member' instead. - Coccinelle didn't handle the hlist_for_each_entry_safe iterator properly, so those had to be fixed up manually. The semantic patch which is mostly the work of Peter Senna Tschudin is here: @@ iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host; type T; expression a,c,d,e; identifier b; statement S; @@ -T b; <+... when != b ( hlist_for_each_entry(a, - b, c, d) S | hlist_for_each_entry_continue(a, - b, c) S | hlist_for_each_entry_from(a, - b, c) S | hlist_for_each_entry_rcu(a, - b, c, d) S | hlist_for_each_entry_rcu_bh(a, - b, c, d) S | hlist_for_each_entry_continue_rcu_bh(a, - b, c) S | for_each_busy_worker(a, c, - b, d) S | ax25_uid_for_each(a, - b, c) S | ax25_for_each(a, - b, c) S | inet_bind_bucket_for_each(a, - b, c) S | sctp_for_each_hentry(a, - b, c) S | sk_for_each(a, - b, c) S | sk_for_each_rcu(a, - b, c) S | sk_for_each_from -(a, b) +(a) S + sk_for_each_from(a) S | sk_for_each_safe(a, - b, c, d) S | sk_for_each_bound(a, - b, c) S | hlist_for_each_entry_safe(a, - b, c, d, e) S | hlist_for_each_entry_continue_rcu(a, - b, c) S | nr_neigh_for_each(a, - b, c) S | nr_neigh_for_each_safe(a, - b, c, d) S | nr_node_for_each(a, - b, c) S | nr_node_for_each_safe(a, - b, c, d) S | - for_each_gfn_sp(a, c, d, b) S + for_each_gfn_sp(a, c, d) S | - for_each_gfn_indirect_valid_sp(a, c, d, b) S + for_each_gfn_indirect_valid_sp(a, c, d) S | for_each_host(a, - b, c) S | for_each_host_safe(a, - b, c, d) S | for_each_mesh_entry(a, - b, c, d) S ) ...+> [akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c] [akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c] [akpm@linux-foundation.org: checkpatch fixes] [akpm@linux-foundation.org: fix warnings] [akpm@linux-foudnation.org: redo intrusive kvm changes] Tested-by: Peter Senna Tschudin <peter.senna@gmail.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Gleb Natapov <gleb@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-27 17:06:00 -08:00
mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time ago with promise that one day it will be possible to implement page cache with bigger chunks than PAGE_SIZE. This promise never materialized. And unlikely will. We have many places where PAGE_CACHE_SIZE assumed to be equal to PAGE_SIZE. And it's constant source of confusion on whether PAGE_CACHE_* or PAGE_* constant should be used in a particular case, especially on the border between fs and mm. Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much breakage to be doable. Let's stop pretending that pages in page cache are special. They are not. The changes are pretty straight-forward: - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN}; - page_cache_get() -> get_page(); - page_cache_release() -> put_page(); This patch contains automated changes generated with coccinelle using script below. For some reason, coccinelle doesn't patch header files. I've called spatch for them manually. The only adjustment after coccinelle is revert of changes to PAGE_CAHCE_ALIGN definition: we are going to drop it later. There are few places in the code where coccinelle didn't reach. I'll fix them manually in a separate patch. Comments and documentation also will be addressed with the separate patch. virtual patch @@ expression E; @@ - E << (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ expression E; @@ - E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ @@ - PAGE_CACHE_SHIFT + PAGE_SHIFT @@ @@ - PAGE_CACHE_SIZE + PAGE_SIZE @@ @@ - PAGE_CACHE_MASK + PAGE_MASK @@ expression E; @@ - PAGE_CACHE_ALIGN(E) + PAGE_ALIGN(E) @@ expression E; @@ - page_cache_get(E) + get_page(E) @@ expression E; @@ - page_cache_release(E) + put_page(E) Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-01 15:29:47 +03:00
mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time ago with promise that one day it will be possible to implement page cache with bigger chunks than PAGE_SIZE. This promise never materialized. And unlikely will. We have many places where PAGE_CACHE_SIZE assumed to be equal to PAGE_SIZE. And it's constant source of confusion on whether PAGE_CACHE_* or PAGE_* constant should be used in a particular case, especially on the border between fs and mm. Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much breakage to be doable. Let's stop pretending that pages in page cache are special. They are not. The changes are pretty straight-forward: - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN}; - page_cache_get() -> get_page(); - page_cache_release() -> put_page(); This patch contains automated changes generated with coccinelle using script below. For some reason, coccinelle doesn't patch header files. I've called spatch for them manually. The only adjustment after coccinelle is revert of changes to PAGE_CAHCE_ALIGN definition: we are going to drop it later. There are few places in the code where coccinelle didn't reach. I'll fix them manually in a separate patch. Comments and documentation also will be addressed with the separate patch. virtual patch @@ expression E; @@ - E << (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ expression E; @@ - E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ @@ - PAGE_CACHE_SHIFT + PAGE_SHIFT @@ @@ - PAGE_CACHE_SIZE + PAGE_SIZE @@ @@ - PAGE_CACHE_MASK + PAGE_MASK @@ expression E; @@ - PAGE_CACHE_ALIGN(E) + PAGE_ALIGN(E) @@ expression E; @@ - page_cache_get(E) + get_page(E) @@ expression E; @@ - page_cache_release(E) + put_page(E) Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-01 15:29:47 +03:00
lib/string_helpers.c: change semantics of string_escape_mem The current semantics of string_escape_mem are inadequate for one of its current users, vsnprintf(). If that is to honour its contract, it must know how much space would be needed for the entire escaped buffer, and string_escape_mem provides no way of obtaining that (short of allocating a large enough buffer (~4 times input string) to let it play with, and that's definitely a big no-no inside vsnprintf). So change the semantics for string_escape_mem to be more snprintf-like: Return the size of the output that would be generated if the destination buffer was big enough, but of course still only write to the part of dst it is allowed to, and (contrary to snprintf) don't do '\0'-termination. It is then up to the caller to detect whether output was truncated and to append a '\0' if desired. Also, we must output partial escape sequences, otherwise a call such as snprintf(buf, 3, "%1pE", "\123") would cause printf to write a \0 to buf[2] but leaving buf[0] and buf[1] with whatever they previously contained. This also fixes a bug in the escaped_string() helper function, which used to unconditionally pass a length of "end-buf" to string_escape_mem(); since the latter doesn't check osz for being insanely large, it would happily write to dst. For example, kasprintf(GFP_KERNEL, "something and then %pE", ...); is an easy way to trigger an oops. In test-string_helpers.c, the -ENOMEM test is replaced with testing for getting the expected return value even if the buffer is too small. We also ensure that nothing is written (by relying on a NULL pointer deref) if the output size is 0 by passing NULL - this has to work for kasprintf("%pE") to work. In net/sunrpc/cache.c, I think qword_add still has the same semantics. Someone should definitely double-check this. In fs/proc/array.c, I made the minimum possible change, but longer-term it should stop poking around in seq_file internals. [andriy.shevchenko@linux.intel.com: simplify qword_add] [andriy.shevchenko@linux.intel.com: add missed curly braces] Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-15 16:17:28 -07:00
lib/string_helpers.c: change semantics of string_escape_mem The current semantics of string_escape_mem are inadequate for one of its current users, vsnprintf(). If that is to honour its contract, it must know how much space would be needed for the entire escaped buffer, and string_escape_mem provides no way of obtaining that (short of allocating a large enough buffer (~4 times input string) to let it play with, and that's definitely a big no-no inside vsnprintf). So change the semantics for string_escape_mem to be more snprintf-like: Return the size of the output that would be generated if the destination buffer was big enough, but of course still only write to the part of dst it is allowed to, and (contrary to snprintf) don't do '\0'-termination. It is then up to the caller to detect whether output was truncated and to append a '\0' if desired. Also, we must output partial escape sequences, otherwise a call such as snprintf(buf, 3, "%1pE", "\123") would cause printf to write a \0 to buf[2] but leaving buf[0] and buf[1] with whatever they previously contained. This also fixes a bug in the escaped_string() helper function, which used to unconditionally pass a length of "end-buf" to string_escape_mem(); since the latter doesn't check osz for being insanely large, it would happily write to dst. For example, kasprintf(GFP_KERNEL, "something and then %pE", ...); is an easy way to trigger an oops. In test-string_helpers.c, the -ENOMEM test is replaced with testing for getting the expected return value even if the buffer is too small. We also ensure that nothing is written (by relying on a NULL pointer deref) if the output size is 0 by passing NULL - this has to work for kasprintf("%pE") to work. In net/sunrpc/cache.c, I think qword_add still has the same semantics. Someone should definitely double-check this. In fs/proc/array.c, I made the minimum possible change, but longer-term it should stop poking around in seq_file internals. [andriy.shevchenko@linux.intel.com: simplify qword_add] [andriy.shevchenko@linux.intel.com: add missed curly braces] Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-15 16:17:28 -07:00
sunrpc/cache: make cache flushing more reliable. The caches used to store sunrpc authentication information can be flushed by writing a timestamp to a file in /proc. This timestamp has a one-second resolution and any entry in cache that was last_refreshed *before* that time is treated as expired. This is problematic as it is not possible to reliably flush the cache without interrupting NFS service. If the current time is written to the "flush" file, any entry that was added since the current second started will still be treated as valid. If one second beyond than the current time is written to the file then no entries can be valid until the second ticks over. This will mean that no NFS request will be handled for up to 1 second. To resolve this issue we make two changes: 1/ treat an entry as expired if the timestamp when it was last_refreshed is before *or the same as* the expiry time. This means that current code which writes out the current time will now flush the cache reliably. 2/ when a new entry in added to the cache - set the last_refresh timestamp to 1 second *beyond* the current flush time, when that not in the past. This ensures that newly added entries will always be valid. Now that we have a very reliable way to flush the cache, and also since we are using "since-boot" timestamps which are monotonic, change cache_purge() to set the smallest future flush_time which will work, and leave it there: don't revert to '1'. Also disable the setting of the 'flush_time' far into the future. That has never been useful and is now awkward as it would cause last_refresh times to be strange. Finally: if a request is made to set the 'flush_time' to the current second, assume the intent is to flush the cache and advance it, if necessary, to 1 second beyond the current 'flush_time' so that all active entries will be deemed to be expired. As part of this we need to add a 'cache_detail' arg to cache_init() and cache_fresh_locked() so they can find the current ->flush_time. Signed-off-by: NeilBrown <neilb@suse.com> Reported-by: Olaf Kirch <okir@suse.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2015-10-16 08:59:08 +11:00
sunrpc/cache: make cache flushing more reliable. The caches used to store sunrpc authentication information can be flushed by writing a timestamp to a file in /proc. This timestamp has a one-second resolution and any entry in cache that was last_refreshed *before* that time is treated as expired. This is problematic as it is not possible to reliably flush the cache without interrupting NFS service. If the current time is written to the "flush" file, any entry that was added since the current second started will still be treated as valid. If one second beyond than the current time is written to the file then no entries can be valid until the second ticks over. This will mean that no NFS request will be handled for up to 1 second. To resolve this issue we make two changes: 1/ treat an entry as expired if the timestamp when it was last_refreshed is before *or the same as* the expiry time. This means that current code which writes out the current time will now flush the cache reliably. 2/ when a new entry in added to the cache - set the last_refresh timestamp to 1 second *beyond* the current flush time, when that not in the past. This ensures that newly added entries will always be valid. Now that we have a very reliable way to flush the cache, and also since we are using "since-boot" timestamps which are monotonic, change cache_purge() to set the smallest future flush_time which will work, and leave it there: don't revert to '1'. Also disable the setting of the 'flush_time' far into the future. That has never been useful and is now awkward as it would cause last_refresh times to be strange. Finally: if a request is made to set the 'flush_time' to the current second, assume the intent is to flush the cache and advance it, if necessary, to 1 second beyond the current 'flush_time' so that all active entries will be deemed to be expired. As part of this we need to add a 'cache_detail' arg to cache_init() and cache_fresh_locked() so they can find the current ->flush_time. Signed-off-by: NeilBrown <neilb@suse.com> Reported-by: Olaf Kirch <okir@suse.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2015-10-16 08:59:08 +11:00
llseek: automatically add .llseek fop All file_operations should get a .llseek operation so we can make nonseekable_open the default for future file operations without a .llseek pointer. The three cases that we can automatically detect are no_llseek, seq_lseek and default_llseek. For cases where we can we can automatically prove that the file offset is always ignored, we use noop_llseek, which maintains the current behavior of not returning an error from a seek. New drivers should normally not use noop_llseek but instead use no_llseek and call nonseekable_open at open time. Existing drivers can be converted to do the same when the maintainer knows for certain that no user code relies on calling seek on the device file. The generated code is often incorrectly indented and right now contains comments that clarify for each added line why a specific variant was chosen. In the version that gets submitted upstream, the comments will be gone and I will manually fix the indentation, because there does not seem to be a way to do that using coccinelle. Some amount of new code is currently sitting in linux-next that should get the same modifications, which I will do at the end of the merge window. Many thanks to Julia Lawall for helping me learn to write a semantic patch that does all this. ===== begin semantic patch ===== // This adds an llseek= method to all file operations, // as a preparation for making no_llseek the default. // // The rules are // - use no_llseek explicitly if we do nonseekable_open // - use seq_lseek for sequential files // - use default_llseek if we know we access f_pos // - use noop_llseek if we know we don't access f_pos, // but we still want to allow users to call lseek // @ open1 exists @ identifier nested_open; @@ nested_open(...) { <+... nonseekable_open(...) ...+> } @ open exists@ identifier open_f; identifier i, f; identifier open1.nested_open; @@ int open_f(struct inode *i, struct file *f) { <+... ( nonseekable_open(...) | nested_open(...) ) ...+> } @ read disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ read_no_fpos disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { ... when != off } @ write @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ write_no_fpos @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { ... when != off } @ fops0 @ identifier fops; @@ struct file_operations fops = { ... }; @ has_llseek depends on fops0 @ identifier fops0.fops; identifier llseek_f; @@ struct file_operations fops = { ... .llseek = llseek_f, ... }; @ has_read depends on fops0 @ identifier fops0.fops; identifier read_f; @@ struct file_operations fops = { ... .read = read_f, ... }; @ has_write depends on fops0 @ identifier fops0.fops; identifier write_f; @@ struct file_operations fops = { ... .write = write_f, ... }; @ has_open depends on fops0 @ identifier fops0.fops; identifier open_f; @@ struct file_operations fops = { ... .open = open_f, ... }; // use no_llseek if we call nonseekable_open //////////////////////////////////////////// @ nonseekable1 depends on !has_llseek && has_open @ identifier fops0.fops; identifier nso ~= "nonseekable_open"; @@ struct file_operations fops = { ... .open = nso, ... +.llseek = no_llseek, /* nonseekable */ }; @ nonseekable2 depends on !has_llseek @ identifier fops0.fops; identifier open.open_f; @@ struct file_operations fops = { ... .open = open_f, ... +.llseek = no_llseek, /* open uses nonseekable */ }; // use seq_lseek for sequential files ///////////////////////////////////// @ seq depends on !has_llseek @ identifier fops0.fops; identifier sr ~= "seq_read"; @@ struct file_operations fops = { ... .read = sr, ... +.llseek = seq_lseek, /* we have seq_read */ }; // use default_llseek if there is a readdir /////////////////////////////////////////// @ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier readdir_e; @@ // any other fop is used that changes pos struct file_operations fops = { ... .readdir = readdir_e, ... +.llseek = default_llseek, /* readdir is present */ }; // use default_llseek if at least one of read/write touches f_pos ///////////////////////////////////////////////////////////////// @ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read.read_f; @@ // read fops use offset struct file_operations fops = { ... .read = read_f, ... +.llseek = default_llseek, /* read accesses f_pos */ }; @ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, ... + .llseek = default_llseek, /* write accesses f_pos */ }; // Use noop_llseek if neither read nor write accesses f_pos /////////////////////////////////////////////////////////// @ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; identifier write_no_fpos.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, .read = read_f, ... +.llseek = noop_llseek, /* read and write both use no f_pos */ }; @ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write_no_fpos.write_f; @@ struct file_operations fops = { ... .write = write_f, ... +.llseek = noop_llseek, /* write uses no f_pos */ }; @ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; @@ struct file_operations fops = { ... .read = read_f, ... +.llseek = noop_llseek, /* read uses no f_pos */ }; @ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; @@ struct file_operations fops = { ... +.llseek = noop_llseek, /* no read or write fn */ }; ===== End semantic patch ===== Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Julia Lawall <julia@diku.dk> Cc: Christoph Hellwig <hch@infradead.org>
2010-08-15 18:52:59 +02:00
llseek: automatically add .llseek fop All file_operations should get a .llseek operation so we can make nonseekable_open the default for future file operations without a .llseek pointer. The three cases that we can automatically detect are no_llseek, seq_lseek and default_llseek. For cases where we can we can automatically prove that the file offset is always ignored, we use noop_llseek, which maintains the current behavior of not returning an error from a seek. New drivers should normally not use noop_llseek but instead use no_llseek and call nonseekable_open at open time. Existing drivers can be converted to do the same when the maintainer knows for certain that no user code relies on calling seek on the device file. The generated code is often incorrectly indented and right now contains comments that clarify for each added line why a specific variant was chosen. In the version that gets submitted upstream, the comments will be gone and I will manually fix the indentation, because there does not seem to be a way to do that using coccinelle. Some amount of new code is currently sitting in linux-next that should get the same modifications, which I will do at the end of the merge window. Many thanks to Julia Lawall for helping me learn to write a semantic patch that does all this. ===== begin semantic patch ===== // This adds an llseek= method to all file operations, // as a preparation for making no_llseek the default. // // The rules are // - use no_llseek explicitly if we do nonseekable_open // - use seq_lseek for sequential files // - use default_llseek if we know we access f_pos // - use noop_llseek if we know we don't access f_pos, // but we still want to allow users to call lseek // @ open1 exists @ identifier nested_open; @@ nested_open(...) { <+... nonseekable_open(...) ...+> } @ open exists@ identifier open_f; identifier i, f; identifier open1.nested_open; @@ int open_f(struct inode *i, struct file *f) { <+... ( nonseekable_open(...) | nested_open(...) ) ...+> } @ read disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ read_no_fpos disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { ... when != off } @ write @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ write_no_fpos @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { ... when != off } @ fops0 @ identifier fops; @@ struct file_operations fops = { ... }; @ has_llseek depends on fops0 @ identifier fops0.fops; identifier llseek_f; @@ struct file_operations fops = { ... .llseek = llseek_f, ... }; @ has_read depends on fops0 @ identifier fops0.fops; identifier read_f; @@ struct file_operations fops = { ... .read = read_f, ... }; @ has_write depends on fops0 @ identifier fops0.fops; identifier write_f; @@ struct file_operations fops = { ... .write = write_f, ... }; @ has_open depends on fops0 @ identifier fops0.fops; identifier open_f; @@ struct file_operations fops = { ... .open = open_f, ... }; // use no_llseek if we call nonseekable_open //////////////////////////////////////////// @ nonseekable1 depends on !has_llseek && has_open @ identifier fops0.fops; identifier nso ~= "nonseekable_open"; @@ struct file_operations fops = { ... .open = nso, ... +.llseek = no_llseek, /* nonseekable */ }; @ nonseekable2 depends on !has_llseek @ identifier fops0.fops; identifier open.open_f; @@ struct file_operations fops = { ... .open = open_f, ... +.llseek = no_llseek, /* open uses nonseekable */ }; // use seq_lseek for sequential files ///////////////////////////////////// @ seq depends on !has_llseek @ identifier fops0.fops; identifier sr ~= "seq_read"; @@ struct file_operations fops = { ... .read = sr, ... +.llseek = seq_lseek, /* we have seq_read */ }; // use default_llseek if there is a readdir /////////////////////////////////////////// @ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier readdir_e; @@ // any other fop is used that changes pos struct file_operations fops = { ... .readdir = readdir_e, ... +.llseek = default_llseek, /* readdir is present */ }; // use default_llseek if at least one of read/write touches f_pos ///////////////////////////////////////////////////////////////// @ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read.read_f; @@ // read fops use offset struct file_operations fops = { ... .read = read_f, ... +.llseek = default_llseek, /* read accesses f_pos */ }; @ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, ... + .llseek = default_llseek, /* write accesses f_pos */ }; // Use noop_llseek if neither read nor write accesses f_pos /////////////////////////////////////////////////////////// @ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; identifier write_no_fpos.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, .read = read_f, ... +.llseek = noop_llseek, /* read and write both use no f_pos */ }; @ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write_no_fpos.write_f; @@ struct file_operations fops = { ... .write = write_f, ... +.llseek = noop_llseek, /* write uses no f_pos */ }; @ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; @@ struct file_operations fops = { ... .read = read_f, ... +.llseek = noop_llseek, /* read uses no f_pos */ }; @ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; @@ struct file_operations fops = { ... +.llseek = noop_llseek, /* no read or write fn */ }; ===== End semantic patch ===== Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Julia Lawall <julia@diku.dk> Cc: Christoph Hellwig <hch@infradead.org>
2010-08-15 18:52:59 +02:00