- 08 4月, 2009 1 次提交
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由 Linus Torvalds 提交于
The code that enables branch tracing for all (non-constant) branches plays games with the preprocessor and #define's the C 'if ()' construct to do tracing. That's all fine, but it fails for some unusual but valid C code that is sometimes used in macros, notably by the intel-iommu code: if (i=drhd->iommu, drhd->ignored) .. because now the preprocessor complains about multiple arguments to the 'if' macro. So make the macro expansion of this particularly horrid trick use varargs, and handle the case of comma-expressions in if-statements. Use another macro to do it cleanly in just one place. This replaces a patch by David (and acked by Steven) that did this all inside that one already-too-horrid macro. Tested-by: NIngo Molnar <mingo@elte.hu> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 07 4月, 2009 39 次提交
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git://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound-2.6由 Linus Torvalds 提交于
* 'for-2.6.30' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound-2.6: ASoC: TWL4030: Compillation error fix
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git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6由 Linus Torvalds 提交于
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6: (36 commits) ALSA: hda - Add VREF powerdown sequence for another board ALSA: oss - volume control for CSWITCH and CROUTE ALSA: hda - add missing comma in ad1884_slave_vols sound: usb-audio: allow period sizes less than 1 ms sound: usb-audio: save data packet interval in audioformat structure sound: usb-audio: remove check_hw_params_convention() sound: usb-audio: show sample format width in proc file ASoC: fsl_dma: Pass the proper device for dma mapping routines ASoC: Fix null dereference in ak4535_remove() ALSA: hda - enable SPDIF output for Intel DX58SO board ALSA: snd-atmel-abdac: increase periods_min to 6 instead of 4 ALSA: snd-atmel-abdac: replace bus_id with dev_name() ALSA: snd-atmel-ac97c: replace bus_id with dev_name() ALSA: snd-atmel-ac97c: cleanup registers when removing driver ALSA: snd-atmel-ac97c: do a proper reset of the external codec ALSA: snd-atmel-ac97c: enable interrupts to catch events for error reporting ALSA: snd-atmel-ac97c: set correct size for buffer hardware parameter ALSA: snd-atmel-ac97c: do not overwrite OCA and ICA when assigning channels ALSA: snd-atmel-ac97c: remove dead break statements after return in switch case ALSA: snd-atmel-ac97c: cleanup register definitions ...
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git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev由 Linus Torvalds 提交于
* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev: sata_mv: shorten register names sata_mv: workaround errata SATA#13 sata_mv: cosmetic renames sata_mv: workaround errata SATA#26 sata_mv: workaround errata PCI#7 sata_mv: replace 0x1f with ATA_PIO4 (v2) sata_mv: fix irq mask races sata_mv: revert SoC irq breakage libata: ahci enclosure management bios workaround ata: Add TRIM infrastructure ata_piix: VGN-BX297XP wants the controller power up on suspend libata: Remove some redundant casts from pata_octeon_cf.c pata_artop: typo
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git://aeryn.fluff.org.uk/bjdooks/linux由 Linus Torvalds 提交于
* 'i2c-for-2630-v2' of git://aeryn.fluff.org.uk/bjdooks/linux: i2c: imx: Make disable_delay a per-device variable i2c: xtensa s6000 i2c driver powerpc/85xx: i2c-mpc: use new I2C bindings for the Socates board i2c: i2c-mpc: make I2C bus speed configurable i2c: i2c-mpc: use dev based printout function i2c: i2c-mpc: various coding style fixes i2c: imx: Add missing request_mem_region in probe() i2c: i2c-s3c2410: Initialise Samsung I2C controller early i2c-s3c2410: Simplify bus frequency calculation i2c-s3c2410: sda_delay should be in ns, not clock ticks i2c: iMX/MXC support
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git://jdelvare.pck.nerim.net/jdelvare-2.6由 Linus Torvalds 提交于
* 'hwmon-for-linus' of git://jdelvare.pck.nerim.net/jdelvare-2.6: hwmon: Add Asus ATK0110 support hwmon: (lm95241) Convert to new-style i2c driver
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由 Alan Cox 提交于
PCI parallel port devices can IRQ share so we should stop them hogging the line and making a mess on modern PC systems. We know the sharing side works as the PCMCIA driver has shared the parallel port IRQ for some time. Signed-off-by: NAlan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Breno Leitao 提交于
Here are some cleanups, mainly removing unused variables and silly declarations. Signed-off-by: NBreno Leitao <leitao@linux.vnet.ibm.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NAlan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Mike Frysinger 提交于
Signed-off-by: NMike Frysinger <vapier.adi@gmail.com> Signed-off-by: NBryan Wu <cooloney@kernel.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NAlan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Mike Frysinger 提交于
Depend on KGDB_SERIAL_CONSOLE being set to N rather than !Y, since it can be built as a module. Signed-off-by: NMike Frysinger <vapier.adi@gmail.com> Signed-off-by: NBryan Wu <cooloney@kernel.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NAlan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Mike Frysinger 提交于
Signed-off-by: NMike Frysinger <vapier.adi@gmail.com> Signed-off-by: NBryan Wu <cooloney@kernel.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NAlan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Sonic Zhang 提交于
Both software emulated and hardware based CTS and RTS are enabled in serial driver. The CTS RTS PIN connection on BF548 UART port is defined as a modem device not as a host device. In order to test it under Linux, please nake a cross UART cable to exchange CTS and RTS signal. Signed-off-by: NSonic Zhang <sonic.zhang@analog.com> Signed-off-by: NBryan Wu <cooloney@kernel.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NAlan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Sonic Zhang 提交于
Only the CTS bit is affected. Signed-off-by: NSonic Zhang <sonic.zhang@analog.com> Signed-off-by: NBryan Wu <cooloney@kernel.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NAlan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Christian Pellegrin 提交于
(akpm: queued pending confirmation of the new major number) [randy.dunlap@oracle.com: select SERIAL_CORE] Signed-off-by: NChristian Pellegrin <chripell@fsfe.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NAlan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Alan Cox 提交于
This is a low density serial port so needs a real major/minor Signed-off-by: NAlan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Alan Cox 提交于
Avoid using port->tty where possible (makes refcount fixing easier later). Remove unused code (the ioctl path is not used if the device has mget/mset functions) Remove various un-needed typecasts and long names so it could read it to do the changes. Signed-off-by: NAlan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Claudio Scordino 提交于
Use the new general RS485 Linux data structure (introduced by Alan with commit number c26c56c0) in the Cris architecture too (currently, Cris still uses the old private data structure instead of the new one). Signed-off-by: NClaudio Scordino <claudio@evidence.eu.com> Tested-by: NHinko Kocevar <hinko.kocevar@cetrtapot.si> Tested-by: NJanez Cufer <janez.cufer@cetrtapot.si> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NAlan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Adrian Bunk 提交于
tty_driver_kref_get() should be static inline and not extern inline (the latter even changed it's semantics in gcc >= 4.3). Signed-off-by: NAdrian Bunk <bunk@kernel.org> Signed-off-by: NAlan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Miklos Szeredi 提交于
There's a possible deadlock in generic_file_splice_write(), splice_from_pipe() and ocfs2_file_splice_write(): - task A calls generic_file_splice_write() - this calls inode_double_lock(), which locks i_mutex on both pipe->inode and target inode - ordering depends on inode pointers, can happen that pipe->inode is locked first - __splice_from_pipe() needs more data, calls pipe_wait() - this releases lock on pipe->inode, goes to interruptible sleep - task B calls generic_file_splice_write(), similarly to the first - this locks pipe->inode, then tries to lock inode, but that is already held by task A - task A is interrupted, it tries to lock pipe->inode, but fails, as it is already held by task B - ABBA deadlock Fix this by explicitly ordering locks: the outer lock must be on target inode and the inner lock (which is later unlocked and relocked) must be on pipe->inode. This is OK, pipe inodes and target inodes form two nonoverlapping sets, generic_file_splice_write() and friends are not called with a target which is a pipe. Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz> Acked-by: NMark Fasheh <mfasheh@suse.com> Acked-by: NJens Axboe <jens.axboe@oracle.com> Cc: stable@kernel.org Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Ryusuke Konishi 提交于
After a review of user's feedback for finding out other compatibility issues, I found nilfs improperly initializes timestamps in inode; CURRENT_TIME was used there instead of CURRENT_TIME_SEC even though nilfs didn't have nanosecond timestamps on disk. A few users gave us the report that the tar program sometimes failed to expand symbolic links on nilfs, and it turned out to be the cause. Instead of applying the above displacement, I've decided to support nanosecond timestamps on this occation. Fortunetaly, a needless 64-bit field was in the nilfs_inode struct, and I found it's available for this purpose without impact for the users. So, this will do the enhancement and resolve the tar problem. Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Ryusuke Konishi 提交于
The former versions didn't have extra super blocks. This improves the weak point by introducing another super block at unused region in tail of the partition. This doesn't break disk format compatibility; older versions just ingore the secondary super block, and new versions just recover it if it doesn't exist. The partition created by an old mkfs may not have unused region, but in that case, the secondary super block will not be added. This doesn't make more redundant copies of the super block; it is a future work. Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Ryusuke Konishi 提交于
will reduce some lines of segment constructor. Previously, the state was complexly controlled through a list of segments in order to keep consistency in meta data of usage state of segments. Instead, this presents ``calculated'' active flags to userland cleaner program and stop maintaining its real flag on disk. Only by this fake flag, the cleaner cannot exactly know if each segment is reclaimable or not. However, the recent extension of nilfs_sustat ioctl struct (nilfs2-extend-nilfs_sustat-ioctl-struct.patch) can prevent the cleaner from reclaiming in-use segment wrongly. So, now I can apply this for simplification. Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Ryusuke Konishi 提交于
Nilfs creates checkpoints even for garbage collection or metadata updates such as checkpoint mode change. So, user often sees checkpoints created only by such internal operations. This is inconvenient in some situations. For example, application that monitors checkpoints and changes them to snapshots, will fall into an infinite loop because it cannot distinguish internally created checkpoints. This patch solves this sort of problem by adding a flag to checkpoint for identification. Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Ryusuke Konishi 提交于
The sketch file is a file to mark checkpoints with user data. It was experimentally introduced in the original implementation, and now obsolete. The file was handled differently with regular files; the file size got truncated when a checkpoint was created. This stops the special treatment and will treat it as a regular file. Most users are not affected because mkfs.nilfs2 no longer makes this file. Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Ryusuke Konishi 提交于
This adds a missing endian conversion of checksum field in the super block. This fixes compatibility issue on big endian machines which will come to surface after supporting recovery of super block. Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Ryusuke Konishi 提交于
Pekka Enberg advised me: > It would be nice if BUG(), BUG_ON(), and panic() calls would be > converted to proper error handling using WARN_ON() calls. The BUG() > call in nilfs_cpfile_delete_checkpoints(), for example, looks to be > triggerable from user-space via the ioctl() system call. This will follow the comment and keep them to a minimum. Acked-by: NPekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Ryusuke Konishi 提交于
This adds a new argument to the nilfs_sustat structure. The extended field allows to delete volatile active state of segments, which was needed to protect freshly-created segments from garbage collection but has confused code dealing with segments. This extension alleviates the mess and gives room for further simplifications. The volatile active flag is not persistent, so it's eliminable on this occasion without affecting compatibility other than the ioctl change. Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Ryusuke Konishi 提交于
Pekka Enberg suggested converting ->ioctl operations to use ->unlocked_ioctl to avoid BKL. The conversion was verified to be safe, so I will take it on this occasion. Cc: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Ryusuke Konishi 提交于
This removes compat code from the nilfs ioctls and applies the same function for both .ioctl and .compat_ioctl file operations. Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Ryusuke Konishi 提交于
Nilfs ioctl had structures not having fixed sized types such as: struct nilfs_argv { void *v_base; size_t v_nmembs; size_t v_size; int v_index; int v_flags; }; Further, some of them are wrongly aligned: e.g. struct nilfs_cpmode { __u64 cm_cno; int cm_mode; }; The size of wrongly aligned structures varies depending on architectures, and it breaks the identity of ioctl commands, which leads to arch dependent errors. Previously, these are compensated by using compat_ioctl. This fixes these problems and allows removal of compat ioctl. Since this will change sizes of those structures, binary compatibility for the past utilities will once break; new utilities have to be used instead. However, it would be helpful to avoid platform dependent problems in the long term. Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Ryusuke Konishi 提交于
This removes NILFS_IOCTL_TIMEDWAIT command from ioctl interface along with the related flags and wait queue. The command is terrible because it just sleeps in the ioctl. I prefer to avoid this by devising means of event polling in userland program. By reconsidering the userland GC daemon, I found this is possible without changing behaviour of the daemon and sacrificing efficiency. Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Ryusuke Konishi 提交于
This will fix the weird behavior of lscp command in listing continuously created checkpoints; the output of lscp is rewinded regularly for the recent nilfs. As a result of debugging, a defect was found in nilfs_cpfile_do_get_cpinfo() function. Though the function can be repeatedly called to enumerate checkpoints and it can skip invalid checkpoint entries, the index value was not carried between successive calls. The bug has long been present, and came to surface after applying a bugfix nilfs2-fix-problems-of-memory-allocation-in-ioctl.patch, which increased frequency of calling the function. The similar bugfix was already applied for ``snapshots'' by nilfs2-fix-gc-failure-on-volumes-keeping-numerous-snapshots.patch. This fixes the problem by making the index argument bidirectional on the function. Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Pekka Enberg 提交于
This cleans up the strange indirect function calling convention used in nilfs to follow the normal kernel coding style. Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi> Acked-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Ryusuke Konishi 提交于
A few tool developers gave me requests for fixing inconvenient return value of nilfs_get_cpinfo() ioctl; if the requested mode is NILFS_SNAPSHOT and the specified start entry is not a snapshot, the ioctl unnaturally returns one as the number of acquired snapshot item. In addition, the ioctl function returns an ENOENT error for checkpoints within blocks deleted by garbage collection. These behaviors require corrections for programs which enumerate snapshots. This resolves the inconvenience by changing the return values to zero for the above cases. Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Ryusuke Konishi 提交于
This resolves the following failure of nilfs2 cleaner daemon: nilfs_cleanerd[20670]: cannot clean segments: No such file or directory nilfs_cleanerd[20670]: shutdown When creating thousands of snapshots, the cleaner daemon had rarely died as above due to an error returned from the kernel code. After applying the recent patch which fixed memory allocation problems in ioctl (Message-Id: <20081215.155840.105124170.ryusuke@osrg.net>), the problem gets more frequent. It turned out to be a bug of nilfs_ioctl_wrap_copy function and one of its callback routines to read out information of snapshots; if the nilfs_ioctl_wrap_copy function divided a large read request into multiple requests, the second and later requests have failed since a restart position on snapshot meta data was not properly set forward. It's a deficiency of the callback interface that cannot pass the restart position among multiple requests. This patch fixes the issue by allowing nilfs_ioctl_wrap_copy and snapshot read functions to exchange a position argument. Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Ryusuke Konishi 提交于
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Ryusuke Konishi 提交于
The file gcinode.c gives buffer cache functions for on-disk blocks moved in garbage collection. Joern Engel has suggested inserting its explanations in the source file (Message-ID: <20080917144146.GD8750@logfs.org> and <20080917224953.GB14644@logfs.org>). This follows the comment. Cc: Joern Engel <joern@logfs.org> Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Ryusuke Konishi 提交于
Pekka Enberg pointed out that double error handlings found after nilfs_transaction_end() can be avoided by separating abort operation: OK, I don't understand this. The only way nilfs_transaction_end() can fail is if we have NILFS_TI_SYNC set and we fail to construct the segment. But why do we want to construct a segment if we don't commit? I guess what I'm asking is why don't we have a separate nilfs_transaction_abort() function that can't fail for the erroneous case to avoid this double error value tracking thing? This does the separation and renames nilfs_transaction_end() to nilfs_transaction_commit() for clarification. Since, some calls of these functions were used just for exclusion control against the segment constructor, they are replaced with semaphore operations. Acked-by: NPekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Ryusuke Konishi 提交于
This will remove the following unnecessary locks and cleanup code in nilfs_clear_inode(): - unnecessary protection using nilfs_transaction_begin() and nilfs_transaction_end(). - cleanup code of i_dirty list field which is never chained when this function is called. - spinlock used when releasing i_bh field. Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Ryusuke Konishi 提交于
This is another patch for fixing the following problems of a memory copy function in nilfs2 ioctl: (1) It tries to allocate 128KB size of memory even for small objects. (2) Though the function repeatedly tries large memory allocations while reducing the size, GFP_NOWAIT flag is not specified. This increases the possibility of system memory shortage. (3) During the retries of (2), verbose warnings are printed because _GFP_NOWARN flag is not used for the kmalloc calls. The first patch was still doing large allocations by kmalloc which are repeatedly tried while reducing the size. Andi Kleen told me that using copy_from_user for large memory is not good from the viewpoint of preempt latency: On Fri, 12 Dec 2008 21:24:11 +0100, Andi Kleen <andi@firstfloor.org> wrote: > > In the current interface, each data item is copied twice: one is to > > the allocated memory from user space (via copy_from_user), and another > > For such large copies it is better to use multiple smaller (e.g. 4K) > copy user, that gives better real time preempt latencies. Each cfu has a > cond_resched(), but only one, not multiple times in the inner loop. He also advised me that: On Sun, 14 Dec 2008 16:13:27 +0100, Andi Kleen <andi@firstfloor.org> wrote: > Better would be if you could go to PAGE_SIZE. order 0 allocations > are typically the fastest / least likely to stall. > > Also in this case it's a good idea to use __get_free_pages() > directly, kmalloc tends to be become less efficient at larger > sizes. For the function in question, the size of buffer memory can be reduced since the buffer is repeatedly used for a number of small objects. On the other hand, it may incur large preempt latencies for larger buffer because a copy_from_user (and a copy_to_user) was applied only once each cycle. With that, this revision uses the order 0 allocations with __get_free_pages() to fix the original problems. Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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